View Filing Data

Print Document View Excel Document

Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2019	Mar. 20, 2020	Jun. 28, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Registrant Name	Personalis, Inc.
Entity Central Index Key	0001527753
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 513,174,177
Entity Common Stock, Shares Outstanding		31,474,193
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38943
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-5411038
Entity Address, Address Line One	1330 O’Brien Drive
Entity Address, City or Town	Menlo Park
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94025
City Area Code	650
Local Phone Number	752-1300
Entity Interactive Data Current	Yes
Document Annual Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, par value $0.0001
Trading Symbol	PSNL
Security Exchange Name	NASDAQ
Documents Incorporated by Reference	Part III incorporates information by reference from the Registrant’s definitive proxy statement to be filed with the U.S. Securities and Exchange Commission pursuant to Regulation 14A, not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K, in connection with the Registrant’s 2020 annual meeting of stockholders (the “2020 Proxy Statement”).

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 55,046	$ 19,744
Short-term investments	73,243
Accounts receivable, net	3,300	4,457
Inventory and other deferred costs	4,606	3,432
Prepaid expenses and other current assets	3,383	1,926
Total current assets	139,578	29,559
Property and equipment, net	14,106	11,452
Operating lease right-of-use assets	1,845
Other long-term assets	1,762	659
Total assets	157,291	41,670
Current liabilities
Accounts payable	7,337	6,565
Accrued and other current liabilities	6,648	3,392
Contract liabilities	35,977	42,897
Short-term debt		4,996
Total current liabilities	49,962	57,850
Redeemable convertible preferred stock warrant liability		683
Other long-term liabilities	639	121
Total liabilities	50,601	58,654
Commitments and Contingencies (Note 12)
Redeemable convertible preferred stock		89,404
Stockholders’ equity (deficit)
Common stock, $0.0001 par value — 200,000,000 shares authorized and 31,243,029 shares issued and outstanding as of December 31, 2019; 102,700,000 shares authorized and 3,085,307 shares issued and outstanding as of December 31, 2018	3	1
Additional paid-in capital	247,282	9,131
Accumulated other comprehensive loss	(6)	(15)
Accumulated deficit	(140,589)	(115,505)
Total stockholders’ equity (deficit)	106,690	(106,388)
Total liabilities, redeemable convertible preferred stock, and stockholders’ equity (deficit)	$ 157,291	$ 41,670

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	102,700,000
Common stock, shares, issued	31,243,029	3,085,307
Common stock, shares, outstanding	31,243,029	3,085,307

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues	$ 65,207	$ 37,774	$ 9,393
Costs and expenses
Costs of revenues	43,127	25,969	11,736
Research and development	22,418	14,304	9,919
Selling, general and administrative	22,080	11,271	9,901
Total costs and expenses	87,625	51,544	31,556
Loss from operations	(22,418)	(13,770)	(22,163)
Interest income	1,620	293	100
Interest expense	(1,133)	(1,894)	(1,303)
Loss on debt extinguishment	(1,704)	(4,658)
Other (expense) income, net	(1,440)	150	(227)
Loss before income taxes	(25,075)	(19,879)	(23,593)
Provision for income taxes	(9)	(7)	(5)
Net loss	$ (25,084)	$ (19,886)	$ (23,598)
Net loss per share, basic and diluted	$ (1.39)	$ (6.49)	$ (7.78)
Weighted-average shares outstanding, basic and diluted	18,011,470	3,063,157	3,031,636

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (25,084)	$ (19,886)	$ (23,598)
Other comprehensive income (loss), net of tax
Foreign currency translation adjustment	3	(5)	7
Change in unrealized gain on available-for-sale debt securities	6
Comprehensive loss	$ (25,075)	$ (19,891)	$ (23,591)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, beginning balance at Dec. 31, 2016						$ 75,995
Redeemable convertible preferred stock, beginning balance, shares at Dec. 31, 2016						16,806,745
Beginning balance at Dec. 31, 2016	$ (69,841)	$ 1	$ 2,196	$ (17)	$ (72,021)
Beginning balance, shares at Dec. 31, 2016		3,020,842
Proceeds from exercise of stock options	76		76
Proceeds from exercise of stock options, shares		30,625
Stock-based compensation	753		753
Foreign currency translation adjustment	7			7
Net loss	(23,598)				(23,598)
Redeemable convertible preferred stock, ending balance at Dec. 31, 2017						$ 75,995
Redeemable convertible preferred stock, ending balance, shares at Dec. 31, 2017						16,806,745
Ending balance at Dec. 31, 2017	(92,603)	$ 1	3,025	(10)	(95,619)
Ending balance, shares at Dec. 31, 2017		3,051,467
Equity component credited to additional paid-in capital upon Convertible Notes modification on May 31, 2018 and August 20, 2018 (see Note 6)	4,690		4,690
Convertible Notes conversion on September 20, 2018 (see Note 6); including issuance of Series C redeemable convertible preferred stock						$ 13,409
Convertible Notes conversion on September 20, 2018 (see Note 6); including issuance of Series C redeemable convertible preferred stock, shares						1,667,997
Proceeds from exercise of stock options	99		99
Proceeds from exercise of stock options, shares		33,840
Stock-based compensation	1,317		1,317
Foreign currency translation adjustment	(5)			(5)
Net loss	(19,886)				(19,886)
Redeemable convertible preferred stock, ending balance at Dec. 31, 2018	$ 89,404					$ 89,404
Redeemable convertible preferred stock, ending balance, shares at Dec. 31, 2018	18,474,742					18,474,742
Ending balance at Dec. 31, 2018	$ (106,388)	$ 1	9,131	(15)	(115,505)
Ending balance, shares at Dec. 31, 2018		3,085,307
Issuance of common stock warrants	572		572
Redeemable convertible preferred stock, reduction of shares outstanding due to effect of reverse stock split (see Notes 2 and 8)						(39)
Elimination of fractional shares upon reverse stock split (see Notes 2 and 8)		$ (1)	1
Elimination of fractional shares upon reverse stock split (see Notes 2 and 8), shares		(34)
Exercise of common stock warrants	8		8
Exercise of common stock warrants, shares		207,712
Redeemable convertible preferred stock, conversion of Series A, B and C redeemable convertible preferred stock to common stock						$ (89,404)
Redeemable convertible preferred stock, conversion of Series A, B and C redeemable convertible preferred stock to common stock, shares						(18,474,703)
Conversion of Series A, B and C redeemable convertible preferred stock to common stock	89,404	$ 2	89,402
Conversion of Series A, B and C redeemable convertible preferred stock to common stock, shares		18,474,703
Conversion of redeemable convertible preferred stock warrants to common stock warrants	2,086		2,086
Proceeds from initial public offering, net of expenses	139,828	$ 1	139,827
Proceeds from initial public offering, net of expenses, shares		9,109,725
Proceeds from exercise of stock options	713		713
Proceeds from exercise of stock options, shares		287,932
Proceeds from ESPP purchase	684		684
Proceeds from ESPP purchase, shares		77,684
Stock-based compensation	4,858		4,858
Foreign currency translation adjustment	3			3
Unrealized gain on available-for-sale debt securities	6			6
Net loss	(25,084)				(25,084)
Ending balance at Dec. 31, 2019	$ 106,690	$ 3	$ 247,282	$ (6)	$ (140,589)
Ending balance, shares at Dec. 31, 2019		31,243,029

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (25,084)	$ (19,886)	$ (23,598)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Depreciation and amortization	4,748	3,066	1,216
Noncash operating lease cost	982
Stock-based compensation expense	4,858	1,317	753
Loss on debt extinguishment	1,704	4,658
Change in fair value of convertible preferred stock warrant liability	1,403	391	64
Change in fair value of compound derivative instrument		(574)	162
Accretion of noncash interest and debt reduction	156	1,188	928
Other	427	(5)	6
Changes in operating assets and liabilities
Accounts receivable	1,069	(2,519)	(1,203)
Inventories and other deferred costs	(1,174)	(2,068)	(539)
Prepaid expenses and other assets	(2,559)	(1,265)	177
Accounts payable	1,398	2,164	2,635
Accrued and other current liabilities	1,999	997	684
Contract liabilities	(6,920)	18,207	19,072
Other long-term liabilities	(1,076)	(99)	(67)
Net cash (used in) provided by operating activities	(18,069)	5,572	290
Cash flows from investing activities:
Purchase of available-for-sale debt securities	(78,897)
Proceeds from maturities of available-for-sale debt securities	5,700
Purchase of property and equipment	(8,382)	(7,852)	(5,158)
Net cash used in investing activities	(81,579)	(7,852)	(5,158)
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriting discounts and commissions	144,025
Payment of costs related to initial public offering	(4,197)
Proceeds from borrowings	20,000		17,225
Payments of borrowing costs	(490)		(63)
Repayments under borrowing arrangements	(25,000)	(645)	(823)
Debt extinguishment costs	(794)
Proceeds from issuance of common stock under ESPP	684
Proceeds from exercise of stock options	712	76	65
Other	8	(22)
Net cash provided by (used in) financing activities	134,948	(591)	16,404
Effect of exchange rates on cash flows and cash equivalents	2	(2)	4
Net increase (decrease) in cash and cash equivalents	35,302	(2,873)	11,540
Cash and cash equivalents, beginning of period	19,744	22,617	11,077
Cash and cash equivalents, end of period	55,046	19,744	22,617
Supplemental disclosures of cash flow information:
Cash paid for interest	1,257	698	321
Income taxes paid	6	7	5
Supplemental disclosures of noncash investing and financing activities:
Acquisition of property and equipment included in accounts payable and accrued liabilities	$ 41	323	$ 521
Convertible Notes conversion on September 20, 2018 (see Note 6)		$ 13,431

Company and Nature of Business

12 Months Ended

Dec. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Company and Nature of Business

Note 1. Company and Nature of Business

Description of Business

Personalis, Inc. (the “Company”) was incorporated in Delaware on February 21, 2011 and began operations in September 2011. The Company formed a wholly owned subsidiary, Personalis (UK) Ltd., in August 2013. The Company is a growing cancer genomics company transforming the development of next-generation therapies by providing more comprehensive molecular data about each patient’s cancer and immune response. The Company operates and manages its business as one reportable operating segment, which is the sale of sequencing and data analysis services.

Significant Risks and Uncertainties

The Company has incurred net operating losses each year since inception. As of December 31, 2019, the Company had an accumulated deficit of $140.6 million.

In June 2019, the Company completed an initial public offering (“IPO”) of its common stock and raised proceeds of $139.8 million, after deducting underwriting discounts, commissions and offering expenses. Management believes that these proceeds combined with existing sources of liquidity will be sufficient to fund operations for at least one year from the issuance of these consolidated financial statements. However, there can be no assurance that additional financing will not be required or that the Company will be successful in raising additional capital on terms that are acceptable to the Company.

If the Company requires but is unable to obtain additional funding, the Company could be required to modify, delay, or abandon some of its planned future expansion or expenditures or reduce some of its ongoing operating costs, which could harm its business, operating results, financial condition, and ability to achieve its intended business objectives.

Approval of Amended and Restated Certificate of Incorporation

An amended and restated certificate of incorporation, which authorized 200,000,000 shares of common stock and 10,000,000 shares of preferred stock, became effective in June 2019 in connection with the closing of the Company’s IPO. As of December 31, 2019 no shares of preferred stock are outstanding.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Note 2. Summary of Significant Accounting Policies

Basis of Presentation

The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding annual reporting. The consolidated financial statements include the accounts of Personalis, Inc. and its wholly owned subsidiary, Personalis (UK) Ltd. All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The estimates include, but are not limited to, useful lives assigned to long-lived assets, the valuation of common and convertible redeemable preferred stock and related warrants and options, the valuation of the compound derivative instrument, the valuation of stock-based awards, and provisions for income taxes and contingencies. Actual results could differ from these estimates, and such differences could be material to the Company’s consolidated financial position and results of operations.

Reverse Stock Split

On June 4, 2019, the Company filed an amendment to the Company’s amended and restated certificate of incorporation to effect a reverse split of shares of the Company’s common stock and redeemable convertible preferred stock on a four-for-one basis (the “Reverse Stock Split”). The par value of the common stock and redeemable convertible preferred stock was not adjusted as a result of the Reverse Stock Split. All references to common stock, options to purchase common stock, share data, per share data, redeemable convertible preferred stock and related information contained in these consolidated financial statements have been retrospectively adjusted to reflect the effect of the Reverse Stock Split for all periods presented.

Initial Public Offering

On June 20, 2019, the Company completed an IPO in which it issued and sold 9,109,725 shares of its common stock at a public offering price of $17.00 per share. The Company received net proceeds of $139.8 million after deducting underwriting discounts, commissions and offering expenses. Offering expenses were $4.2 million and consisted of fees and expenses incurred in connection with the sale of the Company’s common stock in the IPO, including legal, accounting, printing, and other IPO-related costs, all of which were paid by December 31, 2019.

A warrant to purchase 188,643 shares of our common stock was exercised prior to completion of the IPO. In addition, in connection with the IPO, all shares of the Company’s then-outstanding redeemable convertible preferred stock were automatically converted into 18,474,703 shares of the Company’s common stock, and all then-outstanding warrants to purchase the Company’s convertible preferred stock were automatically converted into warrants to purchase 84,585 shares of the Company’s common stock, of which 62,096 are still outstanding as of December 31, 2019 (see Note 10).

Concentration of Credit Risk and Other Risks and Uncertainties

The Company is subject to credit risk from its portfolio of cash and cash equivalents. The Company’s cash and cash equivalents are deposited with high-quality financial institutions. Deposits at these institutions may, at times, exceed federally insured limits. Management believes these financial institutions are financially sound and, accordingly, that minimal credit risk exists. The Company has not experienced any losses on its deposits of cash and cash equivalents.

The Company also invests in investment‑grade debt instruments and has policy limits for the amount it can invest in any one type of security, except for securities issued or guaranteed by the U.S. government. The goals of the Company’s investment policy are as follows: preservation of principal; liquidity of investments sufficient to meet cash flow requirements; avoidance of inappropriate concentration and credit risk; competitive after‑tax rate of returns; and fiduciary control of cash and investments. Under its investment policy, the Company limits the amounts invested in such securities by credit rating, maturity, investment type, and issuer. As a result, management believes that these financial instruments do not expose the Company to any significant concentrations of credit risk.

The Company purchases various reagents and sequencing materials from sole source suppliers. Any extended interruption in the supply of these materials could result in the Company’s inability to secure sufficient materials to conduct business and meet customer demand.

The Company routinely assesses the creditworthiness of its customers and does not require collateral. The Company has not experienced any material losses related to receivables from individual customers, or groups of customers. The Company maintains an allowance for doubtful accounts, which was $0.1 million and zero as of December 31, 2019 and 2018, respectively. During the year ended December 31, 2019, bad debt expense was $0.1 million and included in selling, general and administrative expenses. The Company had no bad debt expense in 2018 and 2017.

Significant customers are those that represent more than 10% of the Company’s total revenues or accounts receivable balance at each respective balance sheet date. For each significant customer, revenue as a percentage of total revenues and accounts receivable as a percentage of total accounts receivable are as follows:

	Revenue									Accounts Receivable
	Year Ended December 31,									As of December 31,
	2019			2018			2017			2019			2018
VA MVP		67	%		49	%	*				19	%	*
Pfizer Inc.		13	%		10	%	*				23	%		33	%
Merck & Co., Inc.	*				12	%		11	%	*				10	%
Customer A	*			*				13	%	*				17	%
Customer B	*			*				10	%	*				10	%
Indivumed GmbH	*			*			*				30	%	*
* Less than 10% of revenues or accounts receivable

Revenue Recognition

The Company applies the revenue recognition guidance in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“Topic 606”).

Revenue Recognition

The revenue guidance provides a five-step framework through which revenue is recognized when control of promised goods or services is transferred to a customer at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To determine revenue recognition for arrangements that the Company concludes are within the scope of Topic 606, management performs the following five steps: (i) identifies the contract(s) with a customer; (ii) identifies the performance obligations in the contract(s); (iii) determines the transaction price, including whether there are any constraints on variable consideration; (iv) allocates the transaction price to the performance obligations; and (v) recognizes revenue when (or as) the Company satisfies a performance obligation. At contract inception, once a contract is determined to be within the scope of the new revenue standard, the Company assesses whether individual goods or services promised within each contract are distinct and, therefore, represent separate performance obligations.

The Company derives revenues from sequencing and data analysis services to support the development of personalized cancer vaccines and other next-generation cancer immunotherapies. The Company’s contracts are in the form of a combination of signed agreements, statements of work, and/or purchase orders. Under Topic 606, the Company accounts for a contract with a customer when there is approval and commitment from both parties, the rights of the parties are identified, payment terms are identified, the contract has commercial substance, and it is probable that the Company will collect substantially all of the consideration to which it will be entitled.

The sequencing and data analysis services are the only distinct services that meet the definition of a performance obligation and are accounted for as one performance obligation under Topic 606. The Company recognizes revenue from such services at the point in time when control of the test results is transferred to the customer. The Company has elected to exclude all sales and value added taxes from the measurement of the transaction price. Sequencing and data analysis services are based on a fixed price per test.

Payment terms and conditions vary by contract and customer. The Company’s standard payment terms are less than 90 days from the invoice date. In instances where the timing of the Company’s revenue recognition differs from the timing of its invoicing, the Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised services to the customer will be one year or less. After assessing each of its revenue-generating arrangements to determine whether a significant financing component exists, the Company concluded that a significant financing component does not exist in any of its arrangements. The primary purpose of the Company’s invoicing terms is to provide customers with simplified and predictable ways of purchasing the Company’s services and to provide payment protection for the Company.

Practical Expedients and Exemptions

As a practical expedient, the Company recognizes the incremental costs of obtaining contracts, such as sales commissions, as an expense when incurred since the amortization period of the asset the Company otherwise would have recognized is one year or less. Sales commissions are recorded within selling, general, and administrative expenses in the consolidated statements of operations.

Costs of Revenues

The Company’s costs of revenues primarily consist of production materials, personnel costs (e.g., salaries, bonuses, benefit, and stock-based compensation), cost of expensed equipment, consumables and laboratory supplies, information technology (“IT”) and facility costs, and depreciation and service maintenance contracts on capitalized equipment.

Research and Development Expenses

The Company charges research and development costs to expenses as incurred, including lab and automation development costs. The expenses primarily consist of employee-related costs (including stock-based compensation), laboratory and automation supplies and equipment, and related depreciation and amortization expenses.

Stock-Based Compensation

For options granted to employees, non-employees, and directors, stock-based compensation is measured at grant date based on the fair value of the award. The Company determines the grant-date fair value of the options using the Black-Scholes option-pricing model. The Company determines fair value of restricted stock unit awards using the closing market price of the Company’s common stock on the date of grant. The grant-date fair value of awards is amortized over the employees’ requisite service period or the non-employees’ vesting period as the goods are received or services rendered. Forfeitures are accounted for as they occur. Additionally, the Company’s 2019 Employee Stock Purchase Plan is deemed to be a compensatory plan and therefore is included in stock-based compensation expense.

Foreign Currency Translation

The functional currency of the Company’s foreign subsidiary is the British pounds sterling. In preparing its consolidated financial statements, the Company is required to translate the financial statements of this subsidiary from British pounds sterling to U.S. dollars. Accordingly, monetary assets and liabilities of the Company’s subsidiary are remeasured using exchange rates in effect at the end of the period. Costs in the local currency are remeasured using average exchange rates for the period, except for costs related to those consolidated balance sheet items that are remeasured using historical exchange rates. Since the Company’s functional currency is deemed to be the local currency, any gain or loss associated with the translation of its consolidated financial statements is included as a component of stockholders’ equity (deficit), in accumulated other comprehensive income (loss).

Comprehensive Loss

Comprehensive loss includes all changes in equity (net assets) during the period from nonowner sources. The Company’s comprehensive loss consists of its net loss, its cumulative translation adjustments, and its unrealized gains or losses on available-for-sale debt securities.

Income Taxes

The Company uses the asset and liability method under ASC Topic 740, Income Taxes, in accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the consolidated financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Deferred tax expenses or benefits are the result of changes in the deferred tax assets and liabilities. Valuation allowances are established when necessary to reduce deferred tax assets where it is more likely than not that the deferred tax assets will not be realized.

ASC Topic 740 clarifies the accounting for uncertainty in income taxes recognized in the financial statements. ASC Topic 740 provides that a tax benefit from an uncertain tax position may be recognized when it is more likely than not that the position will be sustained upon audit, including resolutions of any related appeals or litigation processes, based on the technical merits of the position. ASC Topic 740 also provides guidance on measurement, derecognition, classification, interest and penalties, accounting in interim periods, disclosure, and transition.

The Company recognizes interest and penalties related to unrecognized tax benefits within the income tax expense line in the accompanying consolidated statements of operations. Accrued interest and penalties are included within the related liability line in the consolidated balance sheets.

Net Loss per Share Attributable to Common Stockholders

Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, the redeemable convertible preferred stock, convertible preferred stock warrants, common stock warrants, common stock subject to repurchase, and stock options are considered to be potentially dilutive securities. Basic and diluted net loss attributable to common stockholders per share is presented in conformity with the two-class method required for participating securities as the redeemable convertible preferred stock is considered a participating security. The Company’s participating securities do not have a contractual obligation to share in the Company’s losses. As such, the net loss is attributed entirely to common stockholders. Because the Company has reported a net loss for the reporting periods presented, the diluted net loss per common share is the same as basic net loss per common share for those periods.

Cash and Cash Equivalents

Cash equivalents consist of highly liquid investments with maturities at the time of purchase of three months or less. Cash equivalents include bank demand deposits and money market accounts that invest primarily in cash, U.S. Treasury bills, notes, and other obligations issued or guaranteed as to principal and interest by the U.S. Government, its agencies or instrumentalities, and repurchase agreements secured by such obligations or cash. Cash equivalents also include commercial paper, which are marketable debt securities recorded at fair value and accounted for in the same manner as other marketable debt securities described below.

Short-term Investments

The Company’s investments in marketable debt securities are classified as available-for-sale and recorded at fair value. Investments with original maturities of greater than three months and remaining maturities of less than one year are classified as short-term investments. Investments with maturities beyond one year may be classified as short-term based on their highly liquid nature and because such marketable securities represent the investment of cash that is available for current operations. Short-term investments primarily consist of U.S. agency bonds, commercial paper, corporate bonds, asset-backed securities, and U.S. treasuries.

Unrealized gains and losses are included in accumulated other comprehensive loss in stockholders’ equity (deficit). Any discount or premium arising at purchase is accreted or amortized to interest income or expense. Realized gains and losses and declines in fair value, if any, judged to be other-than-temporary are reported in other (expense) income, net. When securities are sold, any associated unrealized gain or loss initially recorded as a separate component of stockholders’ equity (deficit) is reclassified out of stockholders’ equity (deficit) on a specific-identification basis and recorded in earnings for the period.

The Company periodically evaluates whether declines in fair values of its investments below their book values are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the marketable security until a forecasted recovery occurs. Factors considered include quoted market prices, recent financial results and operating trends, implied values from any recent transactions or offers of investee securities, credit quality of debt instrument issuers, other publicly available information that may affect the value of the marketable security, duration and severity of the decline in value, and management’s strategy and intentions for holding the marketable security. To date, the Company has not recorded any impairment charges on its marketable securities related to other-than-temporary declines in market value.

Fair Value Measurements

Financial assets and liabilities are recorded at fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The hierarchy below lists three levels of fair value based on the extent to which inputs used in measuring fair value are observable in the market. Observable inputs reflect market data obtained from independent sources while unobservable inputs reflect market assumptions made by the reporting entity.

The three-level hierarchy for the inputs to valuation techniques used to measure fair value is briefly summarized as follows:

Level 1 — Unadjusted quoted prices in active markets that are accessible to the reporting entity at the measurement date for identical assets and liabilities.

Level 2 — Inputs other than quoted prices in active markets for identical assets and liabilities that are observable either directly or indirectly for substantially the full term of the asset or liability. Level 2 inputs include the following:

•

Quoted prices for similar assets and liabilities in active markets.

•

Quoted prices for identical or similar assets or liabilities in markets that are not active.

•

Observable inputs other than quoted prices that are used in the valuation of the assets or liabilities (e.g., interest rate and yield curve quotes at commonly quoted intervals).

•

Inputs that are derived principally from or are corroborated by observable market data by correlation or other means.

Level 3 — Unobservable inputs for the assets or liabilities (i.e., supported by little or no market activity). Level 3 inputs include management’s own assumptions about the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk).

This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value.

Accounts Receivable, net

Trade accounts receivable are recorded at the invoiced amount and are noninterest bearing. At each reporting period, management reviews all outstanding customer balances to determine if the facts and circumstances of each customer relationship indicate the need for a reserve. A reserve is recorded when it is probable that a loss has been incurred based on past events and conditions existing at the date of the financial statements, and the loss is reasonably estimated.

Inventory and Other Deferred Costs

Inventories, consisting of supplies used in the Company’s sequencing and data analysis contracts, are valued at the lower of cost or net realizable value. Cost is determined using actual costs, on a first-in, first-out basis.

Other deferred costs relate to work in process for costs incurred on sequencing and data analysis contracts that have not been completed or recognized as revenues. Other deferred costs represent materials used in sequencing services, labor, and overhead allocations.

Property and Equipment, Net

Property and equipment are recorded at cost, less accumulated depreciation and amortization, and are depreciated on a straight-line basis over the estimated useful lives of the related assets, which is generally three to five years for computer equipment, two years for software, three years for furniture and equipment, and five years for machinery and equipment. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the related asset. Upon retirement or sale, the cost and related accumulated depreciation and amortization are removed from the consolidated balance sheet, and the resulting gain or loss is reflected in the consolidated statements of operations. Maintenance and repairs that are not considered improvements and do not extend the useful lives of the assets are charged to operations as incurred.

Construction-in-process assets consist primarily of computer equipment and machinery and equipment that have not yet been placed in service. These assets are stated at cost and are not depreciated. Once the assets are placed into service, assets are reclassified to the appropriate asset class based on their nature and depreciated in accordance with the useful lives above.

Internally used software, whether purchased or developed, is capitalized at cost and amortized on a straight-line basis over its estimated useful life. Costs associated with internally developed software are expensed until the point at which the project has reached the development stage. Subsequent additions, modifications, or upgrades to internal-use software are capitalized only to the extent that they provide additional functionality. Software maintenance and training costs are expensed in the period in which they are incurred. The capitalization of software requires judgment in determining when a project has reached the development stage and the period over which the Company expects to benefit from the use of that software.

Compound Derivative Instrument

The convertible notes issued in June 2017 (see Note 6) contained embedded features that provided the lenders with multiple settlement alternatives. Certain of these settlement features provided the lenders a right to a fixed number of the Company’s shares upon conversion of the notes (the “conversion option”). Other settlement features provided the lenders the right or the obligation to receive cash or a variable number of shares upon the completion of a capital-raising transaction, change of control, or default of the Company (the “redemption features”).

Certain conversion and redemption features embedded in the convertible notes met the requirements for separate accounting and were accounted for as a single, compound derivative instrument. The compound derivative instrument was recorded at fair value at inception and was subject to remeasurement to fair value at each consolidated balance sheet date, with the change in fair value reflected as other (expense) income in the consolidated statements of operations. The compound derivative instrument was recorded as a compound derivative liability at fair value, which was $0.5 million as of the issuance date and zero and $0.7 million as of December 31, 2018 and 2017, respectively (see Note 5). Upon modification of the convertible notes on August 20, 2018 (see Note 6), the compound derivative instrument was eliminated.

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In May 2014, the FASB issued Accounting Standard Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU No. 2014-09”). Subsequently, the FASB also issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606), which adjusted the effective date of ASU No. 2014-09; ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net), which amends the principal-versus-agent implementation guidance and illustrations in ASU No. 2014-09; ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which clarifies identifying performance obligation and licensing implementation guidance and illustrations in ASU No. 2014-09; and ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, which addresses implementation issues and is intended to reduce the cost and complexity of applying the new revenue standard in ASU No. 2014-09 (collectively, the “Revenue ASUs”).

The Revenue ASUs provide an accounting standard for a single comprehensive model for use in accounting for revenues arising from contracts with customers and supersedes most current revenue recognition guidance. The accounting standard is effective for interim and annual periods beginning after December 15, 2017. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (the full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). The Company performed a detailed review of its revenue agreements and assessed the differences in accounting for such contracts under this guidance compared with previous revenue accounting standards. On January 1, 2017, the Company early adopted ASU No. 2014-09 using the full retrospective method. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements. Results for all periods presented are under ASC Topic 606.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU No. 2016-02”). In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases, which provides clarification to ASU 2016-02. These ASUs (collectively, the “new lease standard”) require an entity to recognize a lease liability and a right-of-use (“ROU”) asset on the balance sheet for leases with lease terms of more than 12 months. Lessor accounting is largely unchanged, while lessees will no longer be provided with a source of off-balance sheet financing. This guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842) —Targeted Improvements, which allows entities to elect a modified retrospective transition method where entities may continue to apply the existing lease guidance during the comparative periods and apply the new lease requirements through a cumulative effect adjustment in the period of adoption rather than in the earliest period presented.

On January 1, 2019, the Company adopted ASU No. 2016-02, and its associated amendments using the modified retrospective transition method by applying the new standard to all leases existing at the date of initial application and not restating comparative periods. There was no cumulative-effect adjustment recorded to retained earnings upon adoption. Under the standard, a lessee is required to recognize a lease liability and ROU asset for all leases. The new guidance also modified the classification criteria and requires additional disclosures to enable users of financial statements to understand the amount, timing, and uncertainty of cash flows arising from leases. Consistent with current guidance, a lessee’s recognition, measurement, and presentation of expenses and cash flows arising from a lease continues to depend primarily on its classification. The Company elected the package of practical expedients permitted under the transition guidance, which allowed the Company to carryforward its historical lease classification, its assessment as to whether a contract was or contains a lease, and its initial direct costs for any leases that existed prior to January 1, 2019. The Company also elected the practical expedient not to separate lease and non-lease components. In addition, the Company elected the short-term lease exception as a practical expedient.

At the date of adoption, the Company derecognized a deferred rent liability in the amount of $0.3 million, and recognized a ROU asset and respective lease liability in the amount of $1.7 million and $2.0 million, respectively. As of December 31, 2019, lease liabilities in the amount of $1.4 million and $0.6 million are included in “Accrued and other current liabilities” and “Other long-term liabilities,” respectively.

New Accounting Pronouncements Not Yet Adopted

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables. The accounting update also made minor changes to the impairment model for available-for-sale debt securities. In November of 2019, the FASB delayed the effective date for Smaller Reporting Companies to the first quarter of 2023. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements and related disclosures. The Company will apply the new guidance by means of a cumulative-effect adjustment to the opening retained earnings as of the beginning of the first reporting period in which the guidance is effective.

JOBS Act Accounting Election

The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has irrevocably elected not to avail itself of this exemption from new or revised accounting standards, and therefore, the Company will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.

Revenues

12 Months Ended

Dec. 31, 2019

Revenue From Contract With Customer [Abstract]

Revenues

Note 3. Revenues

The following table presents the Company’s revenues disaggregated by customer type (in thousands):

	Year Ended December 31,
	2019		2018		2017
VA MVP	$	43,545	$	18,601	$	421
All other customers		21,662		19,173		8,972
Total	$	65,207	$	37,774	$	9,393

Revenues from countries outside of the United States, based on the billing addresses of customers, represented 4%, 3%, and 2% of the Company’s revenues for the years ended December 31, 2019, 2018 ,and 2017, respectively.

Contract Assets and Liabilities

The Company had no contract assets as of December 31, 2019 and 2018.

The Company’s contract liabilities consist of customer deposits in excess of revenues recognized and are presented as current liabilities in the consolidated balance sheets.

The balance of contract liabilities was $36.0 million and $42.9 million as of December 31, 2019 and 2018, respectively. Revenues recognized in 2019, 2018, and 2017 that were included in the contract liability balance at the beginning of each reporting period were $35.4 million, $16.0 million, and $1.1 million, respectively.

Revenues allocated to remaining performance obligations represent contracted revenues that have not yet been recognized (“contracted not recognized revenues”), which include VA MVP contract liabilities and amounts that will be invoiced and recognized as revenues in future periods. Contracted not recognized revenues were $68.8 million as of December 31, 2019, which we expect to recognize as revenues over the next 15 months.

Balance Sheet Details

12 Months Ended

Dec. 31, 2019

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Details

Note 4. Balance Sheet Details

Inventory and other deferred costs consist of the following (in thousands):

	December 31,
	2019		2018
Raw materials	$	1,424	$	2,134
Other deferred costs		3,182		1,298
Total inventory and other deferred costs	$	4,606	$	3,432

Property and equipment, net consists of the following (in thousands):

	December 31,
	2019			2018
Machinery and equipment	$	12,511		$	7,951
Computer equipment		8,855			6,822
Furniture and fixtures		368			150
Leasehold improvement		987			1,016
Capitalized software costs		—			182
Computer software costs		198			202
Construction in progress		234			333
Total	$	23,153		$	16,656
Less: Accumulated depreciation and amortization		(9,047	)		(5,204	)
Property and equipment, net	$	14,106		$	11,452

Depreciation and amortization expense for the years ended December 31, 2019, 2018, and 2017 was $4.7 million, $3.1 million, and $1.2 million, respectively.

Accrued and other current liabilities consist of the following (in thousands):

	December 31,
	2019		2018
Accrued compensation	$	4,147	$	2,843
Operating lease right-of-use liabilities		1,361		—
Accrued liabilities		689		59
Accrued taxes		210		181
Accrued interest		—		207
Deferred rent		—		99
Other current liabilities		241		3
Total accrued and other current liabilities	$	6,648	$	3,392

Fair Value Measurements

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 5. Fair Value Measurements

The following tables show the Company’s financial assets and liabilities measured at fair value on a recurring basis and the level of inputs used in such measurements as of December 31, 2019 and 2018 (in thousands):

	As of December 31, 2019
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Fair Value Level
Assets
Cash and cash equivalents
Cash	$	1,271	$	—	$	—		$	1,271
Money market funds		12,495		—		—			12,495	Level 1
Commercial paper		41,281		—		(1	)		41,280	Level 2
Total cash and cash equivalents		55,047		—		(1	)		55,046
Short-term investments
Commercial paper		17,898		—		(6	)		17,892	Level 2
U.S. government securities		4,011		—		—			4,011	Level 2
Corporate debt securities		13,953		1		(6	)		13,948	Level 2
U.S. agency securities		32,776		20		(2	)		32,794	Level 2
Asset-backed securities		4,598		—		—			4,598	Level 2
Total short-term investments		73,236		21		(14	)		73,243
Total assets measured at fair value	$	128,283	$	21	$	(15	)	$	128,289

	As of December 31, 2018
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Fair Value Level
Assets
Cash and cash equivalents
Cash	$	1,602	$	—	$	—		$	1,602
Money market funds		18,142		—		—			18,142	Level 1
Total cash and cash equivalents		19,744		—		—			19,744
Total assets measured at fair value	$	19,744	$	—	$	—		$	19,744
Liabilities
Long-term liabilities
Convertible preferred stock warrants liability								$	683	Level 3
Total liabilities measured at fair value								$	683

There have been no realized gains or losses on sales of marketable securities for the periods presented. The Company began investing in marketable debt securities during the third quarter of 2019 and, therefore, no security has been in an unrealized loss position for 12 months or greater. The Company determined that it did have the ability and intent to hold all marketable securities that have been in a continuous loss position until maturity or recovery. As of December 31, 2019, the Company does not consider any of its marketable debt securities to be other-than-temporarily impaired.

The Company’s marketable debt securities at December 31, 2019 have maturities due in one year or less, except for debt securities with an aggregate cost basis and fair value of $3.0 million that have maturities of 13 months.

The Black-Scholes option-pricing model was used to estimate the fair value of the convertible preferred stock warrants at the date of issuance and at each subsequent consolidated balance sheet date. The fair value of the convertible preferred stock warrants was also estimated at the time of conversion to common stock warrants (see Note 10). Under this option-pricing model, convertible preferred stock warrants were valued by creating a series of call options with exercise prices based on the liquidation preferences and conversion terms of each equity class. The values of the redeemable convertible preferred stock and common stock are inferred by analyzing these options.

The fair value of each convertible preferred stock warrant was estimated using the Black-Scholes option-pricing model with the assumptions described below. Upon conversion to common stock warrants in the second quarter of 2019 (see Note 10), no further fair value measurements were made. Therefore, there is no activity with respect to periods after the second quarter of 2019. For the periods indicated, the Company has limited historical volatility information available, and the expected volatility was based on actual volatility for comparable public companies projected over the expected terms of the warrants. The Company did not apply a forfeiture rate to the warrants as there is not enough historical information available to estimate such a rate. The risk-free interest rate was based on the U.S. Treasury yield curve over the expected term of the warrants.

	Period Ended	Year Ended	Year Ended
	June 24, 2019	December 31, 2018	December 31, 2017
Expected term (in years)	5.01 - 5.26	5.17 - 7.00	6.75 - 7.50
Volatility	57.20% - 57.24%	55.56% - 56.42%	56.07% - 69.87%
Risk-free interest rate	1.75%	2.58% - 3.01%	1.97% - 2.33%
Dividend yield	–%	–%	–%

The fair value of the compound derivative instrument was estimated at the date of inception in June 2017 and at each subsequent consolidated balance sheet date using a hybrid method that combines probability-weighted and with-or-without methods using unobservable inputs, which are classified as Level 3 within the fair value hierarchy. The primary inputs for this approach included the probability of achieving various settlement scenarios that provide the lenders the right or the obligation to receive cash or a variable number of shares upon the completion of a capital transaction. The probability assumptions related to estimating various settlement scenarios as of December 31, 2018 and 2017, and the inception date ranged between 0.2% and 70%, and a discount rate of 35.1% was applied to estimated future cash flows. After the initial measurement, changes in the fair value of this compound derivative were recorded in other income (expense), net.

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial instruments (in thousands):

	Warrant Liability			Derivative Asset			Derivative Liability
Balance—December 31, 2016	$	59		$	—		$	—
Issuance of convertible preferred stock warrants		169			—			—
Initial fair value of derivative liability		—			—			509
Change in fair value		64			—			162
Balance—December 31, 2017	$	292		$	—		$	671
Initial fair value of derivative asset		—			623			—
Change in fair value		391			(97	)		(671	)
Elimination as a result of debt extinguishment		—			(526	)		—
Balance—December 31, 2018	$	683		$	—		$	—
Change in fair value		1,403			—			—
Reclassification of warrant liability to additional paid in capital on conversion		(2,086	)		—			—
Balance—December 31, 2019	$	—		$	—		$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Borrowings

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Borrowings

Note 6. Borrowings

Amounts outstanding under the Company’s financing arrangements consisted of the following (in thousands):

	December 31,		December 31,
	2019		2018
Credit agreement
Revolving Loan	$	—	$	5,000
Total principal payments due	$	—	$	5,000
Less: Reduction in carrying value		—		(4	)
Total amounts outstanding	$	—	$	4,996
Less: Current portion		—		(4,996	)
Long-Term portion	$	—	$	—

Term Loan

In September 2014, the Company entered into a loan and security agreement with Silicon Valley Bank to borrow up to $3.0 million under an equipment loan to be secured by the equipment financed (the “Term Loan”). On October 3, 2014, the Company borrowed $2.4 million under the Term Loan. The Term Loan required 12 interest-only payments, followed by 36 equal monthly installments of principal, plus interest, which began on October 3, 2015.

In connection with the Term Loan, the Company issued to the bank a warrant exercisable for ten years from the date of grant to purchase 22,489 shares of the Company’s Series B redeemable convertible preferred stock at an exercise price of $4.60 per share (see Note 10).

The estimated fair value of the warrants upon draw down of $0.1 million was based on the Black-Scholes option-pricing model. The Company recorded the fair value of the warrant at issuance as a reduction in the debt-carrying value and as a warrant liability. The debt-carrying value reduction was accreted using the effective interest method as additional interest expense over the contractual period of four years for the Term Loan.

On September 30, 2018, the Term Loan was repaid in full.

Revolving Loan

In June 2017, the Company entered into a $10.0 million revolving loan and security agreement (the “Revolving Loan”) with TriplePoint Capital LLC (“TriplePoint”). Borrowings under the Revolving Loan bear an interest rate of prime, plus 6.75%. The Revolving Loan also has a 5.5% end of term loan payment on the highest outstanding principal amount. The Revolving Loan requires monthly interest-only payments until the maturity date. The Revolving Loan’s original maturity date was December 31, 2018, and in December 2018 the maturity date was further extended until March 22, 2019. Upon determining that the change in cash flows between the previous and current credit facility was not greater than 10%, the Company accounted for the transaction as a debt modification.

As of December 31, 2018, the Company’s outstanding principal under the Revolving Loan was $5.0 million and $5.0 million was available to borrow.

In connection with the Revolving Loan, the Company issued to TriplePoint a warrant to purchase up to 62,096 shares of the Company’s Series C redeemable convertible preferred stock at an exercise price of $8.052 per share exercisable for seven years from June 28, 2017 (see Note 10).

The estimated fair value of the warrant upon draw down of $0.1 million was based on the Black-Scholes option-pricing model. The Company recorded the fair value of the warrant at issuance as a reduction in the debt-carrying value and as a warrant liability. The debt-carrying value reduction was accreted using the effective interest method as additional interest expense over the contractual period of 1.5 years for the Revolving Loan.

The Revolving Loan had an effective interest rate of 19.22% per year. The Revolving Loan interest expense for the year ended December 31, 2018 was $0.9 million. Interest expense for the year ended December 31, 2019 was not material.

The Company accrued $0.2 million as of December 31, 2018 related to accretion of final payment due at maturity per the agreement using the effective interest rate method.

On March 22, 2019, this Revolving Loan was repaid in full.

Growth Capital Loan

On March 22, 2019, the Company entered into a growth capital loan (the “Growth Capital Loan”) with TriplePoint to provide for a $20.0 million growth capital loan facility and as of June 30, 2019, had drawn down the full $20.0 million available under the facility. The Company used $5.1 million of the Growth Capital Loan to repay, in its entirety, all amounts outstanding under the Revolving Loan. Borrowings under the Growth Capital Loan bore interest at a floating rate of prime, plus 5.00%, for borrowings up to $15.0 million and the prime rate plus 6.50% for borrowings greater than $15.0 million. Under the agreement, the Company was required to make monthly interest-only payments through April 1, 2020 and was required to make 36 equal monthly payments of principal, plus accrued interest, from April 1, 2020 through March 1, 2023, when all unpaid principal and interest was to become due and payable. The agreement allowed voluntary prepayment of all, but not part, of the outstanding principal at any time prior to the maturity date, subject to a prepayment fee of 1.00% of the outstanding balance if prepaid in months one through 12 of the loan term. In addition to the final payment, the Company paid an amount equal to 2.75% of each principal amount drawn under this growth capital loan facility.

In connection with the Growth Capital Loan, the Company issued a warrant to purchase 65,502 shares of common stock to TriplePoint at an exercise price of $9.16 per share exercisable for seven years from March 22, 2019. The Company recorded the issuance-date fair value of the warrant of $0.6 million and fees paid to TriplePoint of $0.3 million as a debt discount, which was amortized over the term of the Growth Capital Loan using the effective interest method.

Upon issuance, the Growth Capital Loan had an effective interest rate of 15.23% per year. Interest expense for the year ended December 31, 2019 was $1.0 million.

On August 14, 2019, the Company paid off the Growth Capital Loan in its entirety. In connection with this debt repayment, the Company recorded a $1.7 million loss on extinguishment of debt in the consolidated statements of operations.

Convertible Notes

On June 29, 2017, the Company entered into a convertible promissory note agreement with certain existing redeemable convertible preferred stockholders and third parties (collectively, the “Investors”) for the issuance of convertible promissory notes with a face value of $12.2 million (the “Convertible Notes”). Under the terms of the Convertible Notes agreement, the Convertible Notes bore interest of 8.00% per annum, with a maturity date of June 28, 2018. In the event that the Company issued and sold shares of its equity securities (the “Equity Securities”) to Investors on or before the maturity date in an equity financing with total proceeds to the Company of not less than $10 million (including the conversion of the Convertible Notes or other convertible securities issued for capital raising purposes) (a “Qualified Financing”), then the outstanding principal amount of the Convertible Notes and any unpaid accrued interest would have automatically converted in whole without any further action by the holder into such Equity Securities sold in the Qualified Financing at a conversion price equal to the price paid per share for Equity Securities by the Investors in the Qualified Financing multiplied by 0.8. If the Company consummated a change of control while the Convertible Notes remained outstanding, the Company would have repaid the holders in cash an amount equal to 150% of the outstanding principal amount of the Convertible Notes, plus any unpaid accrued interest on the original principal. The Convertible Notes had customary events of default.

Certain conversion and redemption features of the Convertible Notes met the requirements for separate accounting and were accounted for as a single, compound derivative instrument. The compound derivative instrument was recorded at fair value at inception and was subject to remeasurement to fair value at each consolidated balance sheet date, with any changes in fair value recognized in the consolidated statements of operations as other (expense) income, net. The estimated fair value of the compound derivative instrument was $0.5 million at issuance and was recorded as a reduction in the carrying value of the Convertible Notes and as a single, compound derivative liability. The Convertible Notes carrying value reduction was accreted using the effective interest method as interest expense over the Convertible Notes contractual period of one year. The Convertible Notes had an effective interest rate of 12.69% per year.

On May 31, 2018, the original maturity date for the Convertible Notes was extended to June 28, 2019 (previously June 28, 2018). The maturity date extension was deemed substantial and was accounted for as a debt extinguishment. In connection with the debt extinguishment on May 31, 2018, the fair value of the Convertible Notes was allocated between the carrying amount of the Convertible Notes and accrued interest of $13.1 million, a compound derivative asset of $0.6 million, and an equity component of $3.9 million, which was credited to additional paid-in capital within the consolidated statements of redeemable convertible preferred stock and stockholders’ equity (deficit). A $3.3 million loss on debt extinguishment was also recorded in the consolidated statements of operations. The new carrying value of the Convertible Notes was accreted using the effective interest method as interest expense over the new contractual period of 1.1 years.

On August 20, 2018, the maturity date for the Convertible Notes was extended to September 20, 2018 (previously June 28, 2019). The term change was deemed substantial and was accounted for as a debt extinguishment. In connection with the debt extinguishment on August 20, 2018, the fair value of the Convertible Notes was allocated between the new carrying amount of the Convertible Notes and accrued interest of $13.4 million, and an equity component of $0.8 million, which resulted in a credit to additional paid-in capital. Upon modification, the compound derivative asset was eliminated. A $0.8 million loss on debt extinguishment was also recorded in the consolidated statements of operations. The new carrying value of Convertible Notes was accreted using the effective interest method as interest expense over the new contractual period of one month.

On September 20, 2018, upon the maturity of the Convertible Notes, the carrying amount, including accrued interest of $13.4 million, was converted into 1,667,997 shares of the Company’s Series C redeemable convertible preferred stock at a conversion price equal to $8.052 per share. No gain or loss was recorded on the conversion.

The Convertible Notes interest expense for the year ended December 31, 2018 was $0.9 million.

Leases

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Leases

Note 7. Leases

Operating Lease Obligations

In February 2015, the Company entered into a noncancelable operating lease for approximately 31,280 square feet of space used for its current laboratory and office space. The lease expires on November 30, 2020 and includes an option to extend the term for a period of three years immediately following the expiration of the term with rent payments equal to then current fair market rental for the space.

For the 2018 periods presented, the Company recognized rent expense on a straight-line basis over the noncancelable lease term. The Company’s rent expense was $1.1 million for the year ended December 31, 2018.

In August 2019, the Company entered into a noncancelable operating lease for a co-located data center space. The lease expires on September 1, 2022 and includes an option to extend the term for a period of three years immediately following the expiration of the term with rent payments to be negotiated upon such a renewal.

The Company adopted the new lease standard as of January 1, 2019. In determining the present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date if the rate implicit in the lease is not readily determinable. At the date of adoption, the Company determined the amounts of lease liability related to the laboratory and office space lease using a discount rate of 8.0%, which represented the Company’s incremental borrowing rate. The Company determines its incremental borrowing rate for lease liability using its current borrowing rate, adjusted for various factors including level of collateralization and term. With respect to the lease for co-located data center space, the Company determined the amounts of lease liability using a discount rate of 6.6%, and the Company recognized a $1.1 million operating lease right-of-use asset and lease liability on the lease commencement date in September 2019. The Company determined that the optional renewal periods for both leases were not reasonably certain to be exercised as of the lease commencement dates. As a result, the optional renewal periods were not recognized as part of the right-of-use asset or lease liability.

Operating lease cost for the year ended December 31, 2019 was $1.1 million. Cash paid for operating lease liabilities, included in cash flow from operating activities in the Consolidated Statement of Cash Flows was $1.2 million for the year ended December 31, 2019. As of December 31, 2019, the weighted average remaining lease term for the operating leases was 1.8 years and the weighted average incremental borrowing rate was 7.3%.

Future minimum noncancelable operating lease payments at December 31, 2018, determined in accordance with the Company’s historical lease accounting standard (ASC 840), were as follows (in thousands):

	Amount
2019	$	1,091
2020		1,030
Total future minimum lease payments	$	2,121

Future minimum lease payments under noncancelable operating leases as of December 31, 2019 were as follows (in thousands):

	Amount
2020	$	1,408
2021		403
2022		319
Total future minimum lease payments	$	2,130
Less: Imputed interest		(130	)
Present value of future minimum lease payments	$	2,000
Less: Current portion of operating lease liabilities		(1,361	)
Operating lease liabilities - noncurrent	$	639

Redeemable Convertible Preferred Stock

12 Months Ended

Dec. 31, 2019

Temporary Equity Disclosure [Abstract]

Redeemable Convertible Preferred Stock

Note 8. Redeemable Convertible Preferred Stock

Series A redeemable convertible preferred stock, Series B redeemable convertible preferred stock, and Series C redeemable convertible preferred stock (collectively the “Redeemable Convertible Preferred Stock”) outstanding consisted of the following as of December 31, 2018 and as of immediately prior to the automatic conversion of the Redeemable Convertible Preferred Stock into common stock:

	December 31, 2018
(in thousands, except share and per share data)	Shares Authorized		Shares Issued and Outstanding		Aggregate Liquidation Preference		Issuance Costs		Net Carrying Value		Original Issuance Price Per Share
Series A		31,250,000		7,812,497	$	20,500	$	82	$	20,261	$	2.624
Series B		19,288,150		4,799,548		22,078		31		22,047		4.600
Series C		24,700,000		5,862,697		47,206		110		47,096		8.052
Total redeemable convertible preferred stock		75,238,150		18,474,742	$	89,784	$	223	$	89,404

Immediately prior to the closing of the Company’s IPO, all shares of the Company’s then-outstanding Redeemable Convertible Preferred Stock, as shown in the table above, automatically converted on a one-for-one basis into an aggregate of 18,474,703 shares of common stock. The Reverse Stock Split was effected on a holder-by-holder basis with no fractional shares issued, which resulted in 39 fewer shares of common stock issued as compared to the amounts shown in the above table.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

Note 9. Stock-Based Compensation

2011 Equity Incentive Plan and 2019 Equity Incentive Plan

In 2011, the Company established its 2011 Equity Incentive Plan (the “2011 Plan”) that provided for the granting of stock options to employees and nonemployees of the Company. Under the 2011 Plan, the Company had the ability to issue incentive stock options (“ISOs”), nonstatutory stock options (“NSOs”), stock appreciation rights, restricted stock awards, and restricted stock unit awards (“RSUs”). Options under the 2011 Plan could be granted for periods of up to 10 years. The ISOs could be granted at a price per share not less than the fair value at the date of grant. The exercise price of an ISO granted to a 10% stockholder was not less than 110% of the estimated fair value of the shares on the date of grant, as determined by the board of directors (the “Board”). Options granted to new hires generally vested over a four-year period, with 25% vesting at the end of one year and the remaining vesting monthly thereafter; options granted as merit awards generally vested monthly over a four-year period.

For stock option grants issued prior to December 31, 2015, the Company allowed employees to exercise options granted under the 2011 Plan prior to vesting (early exercise of stock options). The unvested shares are subject to the Company’s repurchase rights at the original purchase price. Initially, the proceeds were recorded as an accrued liability from the early exercise of stock options and reclassified to common stock as the Company’s repurchase rights lapsed. There were zero and 262 unvested shares subject to the Company’s repurchase rights as of December 31, 2019 and 2018, respectively.

The Company’s Board adopted and the Company’s stockholders approved the Company’s 2019 Equity Incentive Plan (the “2019 Plan”) in May 2019 and June 2019, respectively. The 2019 Plan became effective in June 2019 in connection with the Company’s IPO, and no further grants will be made under the 2011 Plan. Shares reserved and remaining available for issuance under the 2011 Plan were added to the 2019 Plan reserve upon its effectiveness.

The 2019 Plan provides for the grant of ISOs, NSOs, stock appreciation rights, restricted stock awards, RSUs, performance-based stock awards, and other forms of equity compensation. Additionally, the 2019 Plan provides for the grant of performance cash awards. ISOs may be granted only to the Company’s employees and to any of the Company’s parent or subsidiary corporation’s employees. All other awards may be granted to employees, including officers, and to non-employee directors and consultants of the Company and any of the Company’s affiliates. The exercise price of a stock option generally cannot be less than 100% of the fair market value of our common stock on the date of grant. Options under the 2019 Plan may be granted for periods of up to 10 years.

At December 31, 2018 there were 4,647,839 shares of common stock available for issuance under the 2011 Plan. At December 31, 2019 there were 4,474,057 shares of common stock available for issuance under the 2011 Plan and 2,769,721 available for issuance under the 2019 Plan.

Stock Option Activity

A summary of the Company’s stock option activity under the 2011 Plan and 2019 Plan for the year ended December 31, 2019 is as follows:

	Outstanding Options
(in thousands, except share and per share data)	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Balance—December 31, 2016		2,112,394		$	1.76		6.41	$	2,451
Options granted		898,510			2.44
Options exercised		(30,625	)		2.12				15
Options cancelled		(95,752	)		3.20
Balance—December 31, 2017		2,884,527		$	1.92		6.61	$	5,860
Options granted		1,386,464			5.68
Options exercised		(34,426	)		2.80				96
Options cancelled		(126,435	)		2.96
Balance—December 31, 2018		4,110,130		$	3.16		6.94	$	24,716
Options granted		988,913			11.81
Options exercised		(287,932	)		2.47
Options cancelled		(79,676	)		6.61
Balance—December 31, 2019		4,731,435		$	4.94		6.60	$	29,730
Options vested and exercisable as of December 31, 2019		2,841,458		$	2.97		5.13	$	22,858

The aggregate intrinsic value of unexercised stock options is calculated as the difference between the closing price of the Company’s common stock of $10.90 on December 31, 2019 and the exercise prices of the underlying stock options. Out-of-the money stock options are excluded from the aggregate intrinsic value.

The weighted-average grant date fair value of options granted was $8.00, $5.68, and $2.44 per share for the twelve months ended December 31, 2019, 2018, and 2017, respectively. As of December 31, 2019, the unrecognized stock-based compensation of unvested options was $9.6 million, which is expected to be recognized over a weighted-average period of 2.8 years.

Restricted Stock Units Activity

A summary of the Company’s RSUs activity under the 2019 Plan for the year ended December 31, 2019 is as follows:

	Unvested Restricted Stock Units
(in thousands, except share and per share data)	Number of Shares		Weighted-Average Grant Date Fair Value		Aggregate Fair Value
Balance—December 31, 2018		—	$	—
RSUs granted		120,000		8.86
RSUs vested		—		—
RSUs cancelled		—		—
Balance—December 31, 2019		120,000	$	8.86	$	1,308

The Company granted RSUs to employees to receive shares of the Company’s common stock. The RSUs awarded are subject to each individual’s continued service to the Company through each applicable vesting date over a three-year period. The Company accounted for the fair value of the RSUs using the closing market price of the Company’s common stock on the date of grant. The aggregate fair value of unvested RSUs is calculated using the closing price of the Company’s common stock of $10.90 on December 31, 2019.

Amortization of stock-based compensation expense related to RSUs in 2019 was not material. As of December 31, 2019, the unrecognized stock-based compensation of unvested RSUs was $1.0 million, which is expected to be recognized over a weighted-average period of 2.9 years.

Valuation of Stock Options

The Company estimated the fair value of stock options using the Black-Scholes option-pricing model. The fair value of stock options is recognized on a straight-line basis over the requisite service periods of the awards.

The fair value of stock options was estimated using the following weighted-average assumptions:

	Year Ended December 31,
	2019	2018	2017
Expected term (in years)	5.00 - 6.87	1.50 - 6.35	5.97 - 6.95
Volatility	56.20 - 63.08%	52.19 - 56.47%	56.05 - 65.78%
Risk-free interest rate	1.53 - 2.52%	2.62 - 2.88%	1.88 - 2.10%
Dividend yield	–%	–%	–%

Expected Term. The expected term is calculated using the simplified method, which is available if there is insufficient historical data about exercise patterns and post-vesting employment termination behavior. The simplified method is based on the vesting period and the contractual term for each grant, or for each vesting tranche for awards with graded vesting. The midpoint of the vesting date and the maximum contractual expiration date is used as the expected term under this method. For awards with multiple vesting tranches, the times from grant until the midpoints for each of the tranches may be averaged to provide an overall expected term.

Expected Volatility. The Company used an average historical stock price volatility of a peer group of publicly traded companies to be representative of its expected future stock price volatility, as the Company did not have sufficient trading history for its common stock. For purposes of identifying these peer companies, the Company considered the industry, stage of development, size, and financial leverage of potential comparable companies. For each grant, the Company measured historical volatility over a period equivalent to the expected term.

Risk-Free Interest Rate. The risk-free interest rate is based on the implied yield currently available on U.S. Treasury zero-coupon issues with remaining terms equivalent to the expected term of a stock award.

Expected Dividend Yield. The Company has not paid and does not anticipate paying any dividends in the near future. Accordingly, the Company has estimated the dividend yield to be zero.

2019 Employee Stock Purchase Plan

In May 2019, the Board adopted the 2019 Employee Stock Purchase Plan (the “ESPP”), which was approved by the Company’s stockholders in June 2019. A total of 250,000 shares of common stock are initially reserved for issuance under the ESPP. The number of shares may be increased in accordance with the terms of the ESPP.

Subject to any plan limitations, the ESPP allows eligible employees to contribute, normally through payroll deductions, up to 15% of their earnings for the purchase of the Company’s common stock at a discounted price per share. The price at which common stock is purchased under the ESPP is equal to 85% of the fair market value of the Company’s common stock on the first or last day of the offering period, whichever is lower. Except for the initial offering period, the ESPP provides for separate six-month offering periods beginning on May 1 and November 1 of each year. The initial offering period ran from June 20, 2019 through October 31, 2019.

During the year ended December 31, 2019, 77,684 shares of common stock were purchased under the ESPP. The total compensation expense related to the ESPP for the year ended December 31, 2019 was $0.3 million. The following range of assumptions were used to calculate stock-based compensation for each stock purchase right granted under the ESPP: weighted-average expected life of 0.37 – 0.5 years; expected volatility of 59.1 – 59.9%; risk-free interest rate of 1.6 - 2.1%; and a zero dividend yield.

Stock-based Compensation Expense

The following is a summary of stock-based compensation expense by function (in thousands):

	Year Ended December 31,
	2019		2018		2017
Costs of revenues	$	480	$	177	$	74
Research and development		903		429		225
Selling, general, and administrative		3,475		711		454
Total stock-based compensation expense	$	4,858	$	1,317	$	753

During the year ended December 31, 2019, 67,418 shares with performance conditions vested. The awards were subject to two vesting criteria: (i) a time-based service criterion, and (ii) a performance criterion of an initial public offering, which were met in connection with our June 20, 2019 IPO. The Company recognized $0.3 million of stock-based compensation expense for all such awards. During the years ended December 31, 2018 and 2017, no shares with performance conditions vested and no stock-based compensation expense was recognized related to shares with performance conditions.

Redeemable Convertible Preferred Stock Warrants

12 Months Ended

Dec. 31, 2019

Convertible Preferred Stock Warrants [Abstract]

Redeemable Convertible Preferred Stock Warrants

Note 10. Redeemable Convertible Preferred Stock Warrants

In September 2014, in connection with the Term Loan (see Note 6), the Company issued a warrant to purchase 22,489 shares of its Series B redeemable convertible preferred stock at an exercise price of $4.60 per share. The estimated fair value of the Series B convertible preferred stock warrant on the date of issuance of $0.1 million was recorded as a debt reduction. As of the issuance date, the fair value of the Series B convertible preferred stock warrant was calculated using the Black-Scholes option-pricing model and was based on a contractual term of ten years, a risk-free interest rate of 2.52%, expected volatility of 66.53%, and 0% expected dividend yield.

In June 2017, as additional consideration for the Revolving Loan (see Note 6), the Company issued a warrant to purchase up to 62,096 shares of its Series C redeemable convertible preferred stock at an exercise price of $8.052, subject to certain adjustments, such as any stock splits, stock dividends, recapitalizations, reclassifications, combinations, or similar transactions. The remaining term of the Series C convertible preferred stock warrant is seven years from June 28, 2017.

The estimated fair value of the Series C convertible preferred stock warrant on the date of issuance of $0.1 million was recorded as a debt reduction. As of the issuance date, the fair value of the Series C convertible preferred stock warrant was calculated using the Black-Scholes option-pricing model and was based on a contractual term of seven years, a risk-free interest rate of 1.97%, expected volatility of 64.33%, and 0% expected dividend yield.

At initial recognition, the convertible preferred stock warrants were recorded at their estimated fair values and were subject to remeasurement at each consolidated balance sheet date, with changes in fair value recognized as a component of net income. As of December 31, 2018, the fair values of the convertible preferred stock warrants were calculated to be $0.7 million.

Immediately prior to the closing of the Company’s IPO, the redeemable convertible preferred stock warrants automatically converted to common stock warrants. As a result of the automatic conversion of the redeemable convertible preferred stock warrants to common stock warrants, the Company revalued the redeemable convertible preferred stock warrants as of the completion of the IPO and reclassified the outstanding preferred stock warrant liability balance to additional paid-in capital with no further remeasurements as the common stock warrants are now deemed permanent equity. The fair value transferred to additional paid-in capital was $2.1 million.

Subsequent to the conversion to a common stock warrant and before the end of the Company’s second quarter ended June 30, 2019, the common stock warrant for 22,489 shares was exercised. As a result, the Company issued 19,069 shares of common stock as the contract allows a net share settlement. Separately, the common stock warrant issued in June 2017 for 62,096 shares was still outstanding as of December 31, 2019.

Common Stock Warrants

12 Months Ended

Dec. 31, 2019

Common Stock Warrants [Abstract]

Common Stock Warrants

Note 11. Common Stock Warrants

In connection with the sale of Series A redeemable convertible preferred stock in August 2011, the Company issued a warrant to purchase 188,643 shares of common stock to an investor who purchased Series A redeemable convertible preferred stock in August 2011 at an exercise price of $0.04 per share. The Company recorded the issuance-date fair value of the warrant of $0.1 million in equity as the warrant met all criteria for equity classification. The common stock warrant was exercised in June 2019 prior to the Company’s IPO and is no longer outstanding as of December 31, 2019.

In connection with the Growth Capital Loan agreement (see Note 6), the Company issued a warrant to purchase 65,502 shares of common stock to the lender at an exercise price of $9.16 per share exercisable for seven years from March 22, 2019. The Company recorded the issuance-date fair value of the warrant of $0.6 million in equity as the warrant met all criteria for equity classification. The warrant is still outstanding as of December 31, 2019.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 12. Commitments and Contingencies

Contingencies

The Company is subject to claims and assessments from time to time in the ordinary course of business. Accruals for litigation and contingencies are reflected in the consolidated financial statements based on management’s assessment, including the advice of legal counsel, of the expected outcome of litigation or other dispute resolution proceedings and/or the expected resolution of contingencies. Liabilities for estimated losses are accrued if the potential losses from any claims or legal proceedings are considered probable and the amounts can be reasonably estimated. Significant judgment is required in both the determination of probability of loss and the determination as to whether the amount can be reasonably estimated. Accruals are based only on information available at the time of the assessment due to the uncertain nature of such matters. As additional information becomes available, management reassesses potential liabilities related to pending claims and litigation and may revise its previous estimates, which could materially affect the Company’s consolidated results of operations in a given period. As of December 31, 2019, the Company was not involved in any material legal proceedings.

Indemnification

In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future, but that have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations.

Net Loss per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Net Loss per Share Attributable to Common Stockholders

Note 13. Net Loss per Share Attributable to Common Stockholders

Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period. Because the Company reported a net loss for the years ended December 31, 2019, 2018, and 2017, the number of shares used to calculate diluted net loss per common share is the same as the number of shares used to calculate basic net loss per common share for those periods presented because the potentially dilutive shares would have been antidilutive if included in the calculation.

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data):

	Year Ended December 31,
	2019			2018			2017
Numerator:
Net loss attributable to common stockholders	$	(25,084	)	$	(19,886	)	$	(23,598	)
Denominator:
Weighted-average shares outstanding		18,011,955			3,063,516			3,035,791
Less: Weighted-average shares subject to repurchase		(485	)		(359	)		(4,155	)
Weighted-average shares outstanding used in computing net loss per share attributable to common stockholders — basic and diluted		18,011,470			3,063,157			3,031,636
Net loss per share attributable to common stockholders—basic and diluted	$	(1.39	)	$	(6.49	)	$	(7.78	)

The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive:

	Year Ended December 31,
	2019		2018		2017
Redeemable convertible preferred stock		—		18,474,742		16,806,746
Conversion of Convertible Notes⁽¹⁾		—		—		1,580,151
Common stock warrants		127,598		188,643		188,643
Series B preferred stock warrant		—		22,489		22,489
Series C preferred stock warrant		—		62,096		62,096
Options to purchase common stock		4,731,435		4,110,130		2,884,527
Unvested early exercised common stock options		—		262		2,213
Unvested Restricted Stock Units		120,000		—		—
Employee Stock Purchase Plan		75,405		—		—
Total		5,054,438		22,858,362		21,546,865

⁽¹⁾ Calculated as $12.2 million principal and $0.5 million accrued but unpaid interest as of December 31, 2017.

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

Note 14. Income Taxes

For financial reporting purposes, loss before income taxes includes the following components (in thousands):

	Year Ended December 31,
	2019			2018			2017
Domestic	$	(25,111	)	$	(19,897	)	$	(23,613	)
Foreign		36			18			20
Loss before income taxes	$	(25,075	)	$	(19,879	)	$	(23,593	)

Provision for Income Taxes

The provision for income taxes consists of the following (in thousands):

	Year Ended December 31,
	2019		2018		2017
Current:
Federal	$	—	$	—	$	—
State		1		2		1
Foreign		8		5		4
Total current		9		7		5
Provision for income taxes	$	9	$	7	$	5

Income tax provision related to continuing operations differ from the amounts computed by applying the statutory income tax rate of 21% to pretax loss in 2019 and 2018; and 35% to pretax loss in 2017 as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
Federal statutory rate		(21	)%		(21	)%		(35	)%
Effect of:
State taxes		(8	)%		(3	)%		(7	)%
Change in valuation allowance		28	%		21	%		(9	)%
Rate impact due to tax reform		–	%		–	%		51	%
Research and development credit		(3	)%		(3	)%		(2	)%
Debt extinguishment		–	%		4	%		–	%
Other		4	%		2	%		2	%
Effective tax rate		–	%		–	%		–	%

Tax Law Changes

The U.S. Tax Cuts and Jobs Act (the “Tax Act”) was enacted on December 22, 2017. The Tax Act reduced the U.S. federal corporate tax rate from 35% in 2017 to 21% in 2018, required companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax deferred, and created new taxes on certain foreign sourced earnings. For the year ended December 31, 2017, the Company remeasured its deferred tax assets and liabilities based on the change in the federal rate to 21%. At December 31, 2018, the Company had completed its accounting for the Tax Act, which, other than the decrease in its gross deferred tax assets, did not have a material impact on the Company’s financial statements.

Deferred Tax Assets and Liabilities

Deferred income taxes reflect the net tax effects of loss and credit carryforwards and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets for federal and state income taxes are as follows (in thousands):

	As of December 31,
	2019			2018
Deferred tax assets:
Net operating loss carryforwards	$	30,375		$	22,441
Research and development credits		6,190			4,634
Deferred revenue		2,154			4,839
Accruals		784			460
Stock-based compensation		787			297
Inventory		—			42
Operating lease liabilities		574			—
Other intangibles		426			458
Other		114			3
Total gross deferred tax assets		41,404			33,174
Less: Valuation allowance		(40,000	)		(32,423	)
Net deferred tax assets	$	1,404		$	751
Deferred tax liabilities:
Property and equipment		(875	)		(751	)
Operating lease right-of-use assets		(529	)		—
Net deferred tax liabilities	$	(1,404	)	$	(751	)

Realization of our deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Because of our lack of U.S. earnings history, the net U.S. deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $7.6 million and $4.5 million for the years ended December 31, 2019 and 2018, respectively.

Net Operating Loss and Tax Credit Carryforwards

As of December 31, 2019, the Company had net operating loss carryforwards for federal income tax purposes of approximately $114.9 million, portions of which will begin to expire in 2031. The Company had a total state net operating loss carryforward of approximately $72.2 million, which will begin to expire in 2031. Utilization of some of the federal and state net operating loss and credit carryforwards are subject to annual limitations due to the “change in ownership” provisions of the Internal Revenue Code of 1986, as amended, and similar state provisions. The annual limitations may result in the expiration of net operating losses and credits before utilization.

The Company has federal credits of approximately $3.0 million, which will begin to expire in 2031 and state research credits of approximately $3.2 million, which have no expiration date. These tax credits are subject to the same limitations discussed above.

Unrecognized Tax Benefits

The Company has incurred net operating losses since inception and does not have any significant unrecognized tax benefits. The Company’s policy is to include interest and penalties related to unrecognized tax benefits, if any, within the provision for taxes in the consolidated statements of operations. If the Company is eventually able to recognize its uncertain positions, the effective tax rate would be reduced. The Company currently has a full valuation allowance against its net deferred tax asset, which would impact the timing of the effective tax rate benefit should any of these uncertain tax positions be favorably settled in the future. Any adjustments to the Company’s uncertain tax positions would result in an adjustment of net operating loss or tax credit carryforwards rather than resulting in a cash outlay.

The Company files U.S. federal income tax returns and various state income tax returns. Because of net operating losses and research credit carryovers, substantially all of the Company’s tax years remain open to examination.

The Company has the following activity relating to unrecognized tax benefits (in thousands):

	As of December 31,
	2019		2018
Beginning balance	$	1,192	$	917
Gross increase—tax provision in current period		389		275
Ending balance	$	1,581	$	1,192

Although it is reasonably possible that certain unrecognized tax benefits may increase or decrease within the next 12 months due to tax examination changes, settlement activities, expirations of statute of limitations, or the impact on recognition and measurement considerations related to the results of published tax cases or other similar activities, the Company does not anticipate any significant changes to unrecognized tax benefits over the next 12 months. During the years ended December 31, 2019, 2018, and 2017, no significant interest or penalties were required to be recognized relating to unrecognized tax benefits.

Selected Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Information (Unaudited)

Note 15. Selected Quarterly Financial Information (Unaudited)

The following tables show a summary of the Company’s quarterly financial information for each of the four quarters of 2019 and 2018 (in thousands, except per share amounts):

	For the Three Months Ended (Unaudited)
	December 31, 2019			September 30, 2019			June 30, 2019			March 31, 2019
Revenues	$	18,154		$	17,153		$	15,825		$	14,075
Gross profit	$	6,565		$	5,629		$	5,902		$	3,984
Net loss	$	(6,645	)	$	(6,885	)	$	(5,869	)	$	(5,685	)
Basic and diluted earnings per share	$	(0.21	)	$	(0.22	)	$	(0.89	)	$	(1.84	)

	For the Three Months Ended (Unaudited)
	December 31, 2018			September 30, 2018			June 30, 2018			March 31, 2018
Revenues	$	13,157		$	11,654		$	8,799		$	4,164
Gross profit	$	4,829		$	4,481		$	2,396		$	99
Net loss	$	(3,555	)	$	(3,641	)	$	(7,315	)	$	(5,375	)
Basic and diluted earnings per share	$	(1.16	)	$	(1.19	)	$	(2.39	)	$	(1.76	)

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Reverse Stock Split

Initial Public Offering

Concentration of Credit Risk and Other Risks and Uncertainties

	Revenue									Accounts Receivable
	Year Ended December 31,									As of December 31,
	2019			2018			2017			2019			2018
VA MVP		67	%		49	%	*				19	%	*
Pfizer Inc.		13	%		10	%	*				23	%		33	%
Merck & Co., Inc.	*				12	%		11	%	*				10	%
Customer A	*			*				13	%	*				17	%
Customer B	*			*				10	%	*				10	%
Indivumed GmbH	*			*			*				30	%	*
* Less than 10% of revenues or accounts receivable

Revenue Recognition

Practical Expedients and Exemptions

Costs of Revenues

Research and Development Expenses

Stock-Based Compensation

Foreign Currency Translation

Comprehensive Loss

Income Taxes

Net Loss per Share Attributable to Common Stockholders

Cash and Cash Equivalents

Short-term Investments

Fair Value Measurements

The three-level hierarchy for the inputs to valuation techniques used to measure fair value is briefly summarized as follows:

Level 1 — Unadjusted quoted prices in active markets that are accessible to the reporting entity at the measurement date for identical assets and liabilities.

•

Quoted prices for similar assets and liabilities in active markets.

•

Quoted prices for identical or similar assets or liabilities in markets that are not active.

•

Observable inputs other than quoted prices that are used in the valuation of the assets or liabilities (e.g., interest rate and yield curve quotes at commonly quoted intervals).

•

Inputs that are derived principally from or are corroborated by observable market data by correlation or other means.

This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value.

Accounts Receivable, net

Inventory and Other Deferred Costs

Property and Equipment, Net

Compound Derivative Instrument

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

New Accounting Pronouncements Not Yet Adopted

JOBS Act Accounting Election

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Schedule of Percentage of Revenues and Accounts Receivables from Customers

For each significant customer, revenue as a percentage of total revenues and accounts receivable as a percentage of total accounts receivable are as follows:

	Revenue									Accounts Receivable
	Year Ended December 31,									As of December 31,
	2019			2018			2017			2019			2018
VA MVP		67	%		49	%	*				19	%	*
Pfizer Inc.		13	%		10	%	*				23	%		33	%
Merck & Co., Inc.	*				12	%		11	%	*				10	%
Customer A	*			*				13	%	*				17	%
Customer B	*			*				10	%	*				10	%
Indivumed GmbH	*			*			*				30	%	*
* Less than 10% of revenues or accounts receivable

Revenues (Tables)

12 Months Ended

Dec. 31, 2019

Disaggregation Of Revenue [Abstract]

Schedule of Revenues Disaggregated by Customer Type

The following table presents the Company’s revenues disaggregated by customer type (in thousands):

	Year Ended December 31,
	2019		2018		2017
VA MVP	$	43,545	$	18,601	$	421
All other customers		21,662		19,173		8,972
Total	$	65,207	$	37,774	$	9,393

Balance Sheet Details (Tables)

12 Months Ended

Dec. 31, 2019

Balance Sheet Related Disclosures [Abstract]

Schedule of Inventory and Other Deferred Costs

Inventory and other deferred costs consist of the following (in thousands):

	December 31,
	2019		2018
Raw materials	$	1,424	$	2,134
Other deferred costs		3,182		1,298
Total inventory and other deferred costs	$	4,606	$	3,432

Schedule of Property and Equipment, Net

Property and equipment, net consists of the following (in thousands):

	December 31,
	2019			2018
Machinery and equipment	$	12,511		$	7,951
Computer equipment		8,855			6,822
Furniture and fixtures		368			150
Leasehold improvement		987			1,016
Capitalized software costs		—			182
Computer software costs		198			202
Construction in progress		234			333
Total	$	23,153		$	16,656
Less: Accumulated depreciation and amortization		(9,047	)		(5,204	)
Property and equipment, net	$	14,106		$	11,452

Schedule of Accrued and Other Current Liabilities

Accrued and other current liabilities consist of the following (in thousands):

	December 31,
	2019		2018
Accrued compensation	$	4,147	$	2,843
Operating lease right-of-use liabilities		1,361		—
Accrued liabilities		689		59
Accrued taxes		210		181
Accrued interest		—		207
Deferred rent		—		99
Other current liabilities		241		3
Total accrued and other current liabilities	$	6,648	$	3,392

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis and Level of Inputs used in such Measurements

	As of December 31, 2019
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Fair Value Level
Assets
Cash and cash equivalents
Cash	$	1,271	$	—	$	—		$	1,271
Money market funds		12,495		—		—			12,495	Level 1
Commercial paper		41,281		—		(1	)		41,280	Level 2
Total cash and cash equivalents		55,047		—		(1	)		55,046
Short-term investments
Commercial paper		17,898		—		(6	)		17,892	Level 2
U.S. government securities		4,011		—		—			4,011	Level 2
Corporate debt securities		13,953		1		(6	)		13,948	Level 2
U.S. agency securities		32,776		20		(2	)		32,794	Level 2
Asset-backed securities		4,598		—		—			4,598	Level 2
Total short-term investments		73,236		21		(14	)		73,243
Total assets measured at fair value	$	128,283	$	21	$	(15	)	$	128,289

	As of December 31, 2018
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Fair Value Level
Assets
Cash and cash equivalents
Cash	$	1,602	$	—	$	—		$	1,602
Money market funds		18,142		—		—			18,142	Level 1
Total cash and cash equivalents		19,744		—		—			19,744
Total assets measured at fair value	$	19,744	$	—	$	—		$	19,744
Liabilities
Long-term liabilities
Convertible preferred stock warrants liability								$	683	Level 3
Total liabilities measured at fair value								$	683

Schedule of Risk-free Interest Rate Based on U.S. Treasury Yield Curve Over Expected Term of Warrants

The risk-free interest rate was based on the U.S. Treasury yield curve over the expected term of the warrants.

	Period Ended	Year Ended	Year Ended
	June 24, 2019	December 31, 2018	December 31, 2017
Expected term (in years)	5.01 - 5.26	5.17 - 7.00	6.75 - 7.50
Volatility	57.20% - 57.24%	55.56% - 56.42%	56.07% - 69.87%
Risk-free interest rate	1.75%	2.58% - 3.01%	1.97% - 2.33%
Dividend yield	–%	–%	–%

Summary of Changes in Fair Value of Level 3 Financial Instruments

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial instruments (in thousands):

	Warrant Liability			Derivative Asset			Derivative Liability
Balance—December 31, 2016	$	59		$	—		$	—
Issuance of convertible preferred stock warrants		169			—			—
Initial fair value of derivative liability		—			—			509
Change in fair value		64			—			162
Balance—December 31, 2017	$	292		$	—		$	671
Initial fair value of derivative asset		—			623			—
Change in fair value		391			(97	)		(671	)
Elimination as a result of debt extinguishment		—			(526	)		—
Balance—December 31, 2018	$	683		$	—		$	—
Change in fair value		1,403			—			—
Reclassification of warrant liability to additional paid in capital on conversion		(2,086	)		—			—
Balance—December 31, 2019	$	—		$	—		$	—

Borrowings (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Summary of Amounts Outstanding Under Company's Financing Arrangements

Amounts outstanding under the Company’s financing arrangements consisted of the following (in thousands):

	December 31,		December 31,
	2019		2018
Credit agreement
Revolving Loan	$	—	$	5,000
Total principal payments due	$	—	$	5,000
Less: Reduction in carrying value		—		(4	)
Total amounts outstanding	$	—	$	4,996
Less: Current portion		—		(4,996	)
Long-Term portion	$	—	$	—

Leases (Tables)

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Schedule of Future Minimum Lease Payments under ASC 840

	Amount
2019	$	1,091
2020		1,030
Total future minimum lease payments	$	2,121

Schedule of Future Minimum Lease Payments under ASC 842

Future minimum lease payments under noncancelable operating leases as of December 31, 2019 were as follows (in thousands):

	Amount
2020	$	1,408
2021		403
2022		319
Total future minimum lease payments	$	2,130
Less: Imputed interest		(130	)
Present value of future minimum lease payments	$	2,000
Less: Current portion of operating lease liabilities		(1,361	)
Operating lease liabilities - noncurrent	$	639

Redeemable Convertible Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2019

Temporary Equity Disclosure [Abstract]

Summary of Redeemable Convertible Preferred Stock Outstanding

	December 31, 2018
(in thousands, except share and per share data)	Shares Authorized		Shares Issued and Outstanding		Aggregate Liquidation Preference		Issuance Costs		Net Carrying Value		Original Issuance Price Per Share
Series A		31,250,000		7,812,497	$	20,500	$	82	$	20,261	$	2.624
Series B		19,288,150		4,799,548		22,078		31		22,047		4.600
Series C		24,700,000		5,862,697		47,206		110		47,096		8.052
Total redeemable convertible preferred stock		75,238,150		18,474,742	$	89,784	$	223	$	89,404

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

A summary of the Company’s stock option activity under the 2011 Plan and 2019 Plan for the year ended December 31, 2019 is as follows:

	Outstanding Options
(in thousands, except share and per share data)	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Balance—December 31, 2016		2,112,394		$	1.76		6.41	$	2,451
Options granted		898,510			2.44
Options exercised		(30,625	)		2.12				15
Options cancelled		(95,752	)		3.20
Balance—December 31, 2017		2,884,527		$	1.92		6.61	$	5,860
Options granted		1,386,464			5.68
Options exercised		(34,426	)		2.80				96
Options cancelled		(126,435	)		2.96
Balance—December 31, 2018		4,110,130		$	3.16		6.94	$	24,716
Options granted		988,913			11.81
Options exercised		(287,932	)		2.47
Options cancelled		(79,676	)		6.61
Balance—December 31, 2019		4,731,435		$	4.94		6.60	$	29,730
Options vested and exercisable as of December 31, 2019		2,841,458		$	2.97		5.13	$	22,858

Summary of Restricted Stock Units Activity

A summary of the Company’s RSUs activity under the 2019 Plan for the year ended December 31, 2019 is as follows:

	Unvested Restricted Stock Units
(in thousands, except share and per share data)	Number of Shares		Weighted-Average Grant Date Fair Value		Aggregate Fair Value
Balance—December 31, 2018		—	$	—
RSUs granted		120,000		8.86
RSUs vested		—		—
RSUs cancelled		—		—
Balance—December 31, 2019		120,000	$	8.86	$	1,308

Summary of Weighted-average Assumptions Used in Determination of Fair Value of Stock Options

The fair value of stock options was estimated using the following weighted-average assumptions:

	Year Ended December 31,
	2019	2018	2017
Expected term (in years)	5.00 - 6.87	1.50 - 6.35	5.97 - 6.95
Volatility	56.20 - 63.08%	52.19 - 56.47%	56.05 - 65.78%
Risk-free interest rate	1.53 - 2.52%	2.62 - 2.88%	1.88 - 2.10%
Dividend yield	–%	–%	–%

Stock Based Compensation Expense by Function

The following is a summary of stock-based compensation expense by function (in thousands):

	Year Ended December 31,
	2019		2018		2017
Costs of revenues	$	480	$	177	$	74
Research and development		903		429		225
Selling, general, and administrative		3,475		711		454
Total stock-based compensation expense	$	4,858	$	1,317	$	753

Net Loss per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss per Share

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data):

	Year Ended December 31,
	2019			2018			2017
Numerator:
Net loss attributable to common stockholders	$	(25,084	)	$	(19,886	)	$	(23,598	)
Denominator:
Weighted-average shares outstanding		18,011,955			3,063,516			3,035,791
Less: Weighted-average shares subject to repurchase		(485	)		(359	)		(4,155	)
Weighted-average shares outstanding used in computing net loss per share attributable to common stockholders — basic and diluted		18,011,470			3,063,157			3,031,636
Net loss per share attributable to common stockholders—basic and diluted	$	(1.39	)	$	(6.49	)	$	(7.78	)

Schedule of Dilutive Securities Excluded from Computation of Diluted Net Loss per Share

	Year Ended December 31,
	2019		2018		2017
Redeemable convertible preferred stock		—		18,474,742		16,806,746
Conversion of Convertible Notes⁽¹⁾		—		—		1,580,151
Common stock warrants		127,598		188,643		188,643
Series B preferred stock warrant		—		22,489		22,489
Series C preferred stock warrant		—		62,096		62,096
Options to purchase common stock		4,731,435		4,110,130		2,884,527
Unvested early exercised common stock options		—		262		2,213
Unvested Restricted Stock Units		120,000		—		—
Employee Stock Purchase Plan		75,405		—		—
Total		5,054,438		22,858,362		21,546,865

⁽¹⁾ Calculated as $12.2 million principal and $0.5 million accrued but unpaid interest as of December 31, 2017.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Loss Before Income Taxes

For financial reporting purposes, loss before income taxes includes the following components (in thousands):

	Year Ended December 31,
	2019			2018			2017
Domestic	$	(25,111	)	$	(19,897	)	$	(23,613	)
Foreign		36			18			20
Loss before income taxes	$	(25,075	)	$	(19,879	)	$	(23,593	)

Schedule of Provision for Income Taxes

The provision for income taxes consists of the following (in thousands):

	Year Ended December 31,
	2019		2018		2017
Current:
Federal	$	—	$	—	$	—
State		1		2		1
Foreign		8		5		4
Total current		9		7		5
Provision for income taxes	$	9	$	7	$	5

Summary of Income Tax Provision Related to Continuing Operations Statutory Income Tax Rate

	Year Ended December 31,
	2019			2018			2017
Federal statutory rate		(21	)%		(21	)%		(35	)%
Effect of:
State taxes		(8	)%		(3	)%		(7	)%
Change in valuation allowance		28	%		21	%		(9	)%
Rate impact due to tax reform		–	%		–	%		51	%
Research and development credit		(3	)%		(3	)%		(2	)%
Debt extinguishment		–	%		4	%		–	%
Other		4	%		2	%		2	%
Effective tax rate		–	%		–	%		–	%

Components of Deferred Tax Assets for Federal and State Income Taxes

Significant components of the Company’s deferred tax assets for federal and state income taxes are as follows (in thousands):

	As of December 31,
	2019			2018
Deferred tax assets:
Net operating loss carryforwards	$	30,375		$	22,441
Research and development credits		6,190			4,634
Deferred revenue		2,154			4,839
Accruals		784			460
Stock-based compensation		787			297
Inventory		—			42
Operating lease liabilities		574			—
Other intangibles		426			458
Other		114			3
Total gross deferred tax assets		41,404			33,174
Less: Valuation allowance		(40,000	)		(32,423	)
Net deferred tax assets	$	1,404		$	751
Deferred tax liabilities:
Property and equipment		(875	)		(751	)
Operating lease right-of-use assets		(529	)		—
Net deferred tax liabilities	$	(1,404	)	$	(751	)

Summary of Unrecognized Tax Benefits

The Company has the following activity relating to unrecognized tax benefits (in thousands):

	As of December 31,
	2019		2018
Beginning balance	$	1,192	$	917
Gross increase—tax provision in current period		389		275
Ending balance	$	1,581	$	1,192

Selected Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Summary of the Quarterly Financial Information

The following tables show a summary of the Company’s quarterly financial information for each of the four quarters of 2019 and 2018 (in thousands, except per share amounts):

	For the Three Months Ended (Unaudited)
	December 31, 2019			September 30, 2019			June 30, 2019			March 31, 2019
Revenues	$	18,154		$	17,153		$	15,825		$	14,075
Gross profit	$	6,565		$	5,629		$	5,902		$	3,984
Net loss	$	(6,645	)	$	(6,885	)	$	(5,869	)	$	(5,685	)
Basic and diluted earnings per share	$	(0.21	)	$	(0.22	)	$	(0.89	)	$	(1.84	)

	For the Three Months Ended (Unaudited)
	December 31, 2018			September 30, 2018			June 30, 2018			March 31, 2018
Revenues	$	13,157		$	11,654		$	8,799		$	4,164
Gross profit	$	4,829		$	4,481		$	2,396		$	99
Net loss	$	(3,555	)	$	(3,641	)	$	(7,315	)	$	(5,375	)
Basic and diluted earnings per share	$	(1.16	)	$	(1.19	)	$	(2.39	)	$	(1.76	)

Company and Nature of Business - Additional Information (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) Segment shares	Dec. 31, 2018 USD ($) shares
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of reportable segments \| Segment		1
Accumulated deficit \| $		$ 140,589	$ 115,505
Proceeds from issuance of common stock after deducting underwriting discounts, commissions and offering expenses upon completion of initial public offering \| $		$ 144,025
Common stock, shares authorized \| shares		200,000,000	102,700,000
Preferred stock, shares authorized \| shares		10,000,000
Preferred stock, shares outstanding \| shares		0
Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Proceeds from issuance of common stock after deducting underwriting discounts, commissions and offering expenses upon completion of initial public offering \| $	$ 139,800

Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Jun. 20, 2019 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)	Jun. 29, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Reverse stock split of common stock, description		four-for-one
Reverse stock split of common stock, ratio		0.25
Offering expenses		$ 4,200,000
Conversion from convertible warrants \| shares	188,643
Allowance for doubtful accounts		100,000	$ 0
Bad debt expense			0	$ 0
Operating lease right-of-use assets		1,845,000
Lease liability		$ 2,000,000
Convertible Notes
Summary Of Significant Accounting Policies [Line Items]
Fair value of compound derivative instrument			$ 0	$ 700,000		$ 500,000
Software
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		2 years
Furniture and Equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		3 years
Machinery and Equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		5 years
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Cumulative-effect adjustment recorded to retained earnings					$ 0
Derecognized deferred rent liability					300,000
Operating lease right-of-use assets					1,700,000
Lease liability					$ 2,000,000
ASU 2016-02 \| Accrued and Other Current Liabilities
Summary Of Significant Accounting Policies [Line Items]
Lease liability		$ 1,400,000
ASU 2016-02 \| Other Long-term Liabilities
Summary Of Significant Accounting Policies [Line Items]
Lease liability		$ 600,000
Minimum \| Computer Equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		3 years
Minimum \| ASU 2014-09
Summary Of Significant Accounting Policies [Line Items]
Standard payment terms		90 days
Maximum \| Computer Equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives		5 years
Maximum \| ASU 2014-09
Summary Of Significant Accounting Policies [Line Items]
Period between payment by customer and transfer of promised services		1 year
Recognition period of incremental costs		1 year
Selling, General and Administrative Expenses
Summary Of Significant Accounting Policies [Line Items]
Bad debt expense		$ 100,000
Common Stock
Summary Of Significant Accounting Policies [Line Items]
Number of shares issued \| shares		9,109,725
Conversion from convertible common stock \| shares		18,474,703
Warrant outstanding \| shares		62,096
IPO
Summary Of Significant Accounting Policies [Line Items]
Reverse stock split of common stock, description		The Reverse Stock Split was effected on a holder-by-holder basis with no fractional shares issued, which resulted in 39 fewer shares of common stock issued as compared to the amounts shown in the above table
Number of shares issued \| shares	9,109,725
Shares issued price per share \| $ / shares	$ 17.00
Proceeds from issuance of common stock after deducting underwriting discounts, commissions and offering expenses upon completion of initial public offering	$ 139,800,000
Conversion from convertible common stock \| shares	18,474,703
IPO \| Common Stock
Summary Of Significant Accounting Policies [Line Items]
Warrant outstanding \| shares		62,096
IPO \| Convertible Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Conversion from convertible warrants to purchase common stock \| shares	84,585

Summary of Significant Accounting Policies - Schedule of Percentage of Revenues and Accounts Receivables from Customers (Details) - Customer	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue \| VA MVP
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	67.00%	49.00%
Revenue \| Merck & Co., Inc.
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		12.00%	11.00%
Revenue \| Pfizer Inc.
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	13.00%	10.00%
Revenue \| Customer A
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage			13.00%
Revenue \| Customer B
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage			10.00%
Accounts Receivable \| VA MVP
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	19.00%
Accounts Receivable \| Indivumed GmbH
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	30.00%
Accounts Receivable \| Merck & Co., Inc.
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		10.00%
Accounts Receivable \| Pfizer Inc.
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	23.00%	33.00%
Accounts Receivable \| Customer A
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		17.00%
Accounts Receivable \| Customer B
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		10.00%

Summary of Significant Accounting Policies - Schedule of Percentage of Revenues and Accounts Receivables from Customers (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2019
Accounts Receivable \| Minimum \| Customer
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	10.00%

Revenues - Schedule of Revenues Disaggregated by Customer Type (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Revenues	$ 18,154	$ 17,153	$ 15,825	$ 14,075	$ 13,157	$ 11,654	$ 8,799	$ 4,164	$ 65,207	$ 37,774	$ 9,393
VA MVP
Disaggregation Of Revenue [Line Items]
Revenues									43,545	18,601	421
All Other Customers
Disaggregation Of Revenue [Line Items]
Revenues									$ 21,662	$ 19,173	$ 8,972

Revenues - Additional Information (Details) - USD ($)	12 Months Ended
Revenues - Additional Information (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Contract assets	$ 0	$ 0
Contract liabilities	36,000,000	42,900,000
Contract liability, revenue recognized	$ 35,400,000	$ 16,000,000	$ 1,100,000
Customer Concentration Risk \| Revenues \| Maximum \| Outside of United States
Disaggregation Of Revenue [Line Items]
Revenue	4.00%	3.00%	2.00%

Revenues - Additional Information (Details 1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01 $ in Millions	Dec. 31, 2019 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligation, amount	$ 68.8
Remaining performance obligation, expected time of satisfaction	15 months

Balance Sheet Details - Schedule of Inventory and Other Deferred Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Inventory And Other Deferred Costs [Abstract]
Raw materials	$ 1,424	$ 2,134
Other deferred costs	3,182	1,298
Total inventory and other deferred costs	$ 4,606	$ 3,432

Balance Sheet Details - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Total	$ 23,153	$ 16,656
Less: Accumulated depreciation and amortization	(9,047)	(5,204)
Property and equipment, net	14,106	11,452
Machinery and Equipment
Property Plant And Equipment [Line Items]
Total	12,511	7,951
Computer Equipment
Property Plant And Equipment [Line Items]
Total	8,855	6,822
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total	368	150
Leasehold Improvement
Property Plant And Equipment [Line Items]
Total	987	1,016
Capitalized Software Costs
Property Plant And Equipment [Line Items]
Total		182
Computer Software Costs
Property Plant And Equipment [Line Items]
Total	198	202
Construction in Progress
Property Plant And Equipment [Line Items]
Total	$ 234	$ 333

Balance Sheet Details - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Depreciation and amortization expense	$ 4,748	$ 3,066	$ 1,216

Balance Sheet Details - Schedule of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Accrued compensation	$ 4,147	$ 2,843
Operating lease right-of-use liabilities	1,361
Accrued liabilities	689	59
Accrued taxes	210	181
Accrued interest		207
Deferred rent		99
Other current liabilities	241	3
Total accrued and other current liabilities	$ 6,648	$ 3,392

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis and Level of Inputs used in such Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Cash and cash equivalents, Adjusted Cost	$ 55,046	$ 19,744
Fair Value Measurements Recurring
Assets
Cash and cash equivalents, Adjusted Cost	55,047	19,744
Cash and cash equivalents, Unrealized Losses	(1)
Cash and cash equivalents, Fair Value	55,046	19,744
Assets, Adjusted Cost	128,283	19,744
Assets, Unrealized Gains	21
Assets, Unrealized Losses	(15)
Assets, Fair Value	128,289	19,744
Liabilities
Total liabilities measured at fair value		683
Fair Value Measurements Recurring \| Short-term Investments
Assets
Investments, Adjusted Cost	73,236
Investments, Unrealized Gains	21
Investments, Unrealized Losses	(14)
Investments, Fair Value	73,243
Fair Value Measurements Recurring \| Cash
Assets
Cash and cash equivalents, Adjusted Cost	1,271	1,602
Cash and cash equivalents, Fair Value	1,271	1,602
Fair Value Measurements Recurring \| Level 1 \| Money Market Funds
Assets
Cash and cash equivalents, Adjusted Cost	12,495	18,142
Cash and cash equivalents, Fair Value	12,495	18,142
Fair Value Measurements Recurring \| Level 2 \| Commercial Paper
Assets
Cash and cash equivalents, Adjusted Cost	41,281
Cash and cash equivalents, Unrealized Losses	(1)
Cash and cash equivalents, Fair Value	41,280
Fair Value Measurements Recurring \| Level 2 \| Commercial Paper \| Short-term Investments
Assets
Investments, Adjusted Cost	17,898
Investments, Unrealized Losses	(6)
Investments, Fair Value	17,892
Fair Value Measurements Recurring \| Level 2 \| U.S. Government Securities \| Short-term Investments
Assets
Investments, Adjusted Cost	4,011
Investments, Fair Value	4,011
Fair Value Measurements Recurring \| Level 2 \| Corporate Debt Securities \| Short-term Investments
Assets
Investments, Adjusted Cost	13,953
Investments, Unrealized Gains	1
Investments, Unrealized Losses	(6)
Investments, Fair Value	13,948
Fair Value Measurements Recurring \| Level 2 \| U.S. Agency Securities \| Short-term Investments
Assets
Investments, Adjusted Cost	32,776
Investments, Unrealized Gains	20
Investments, Unrealized Losses	(2)
Investments, Fair Value	32,794
Fair Value Measurements Recurring \| Level 2 \| Asset-backed Securities \| Short-term Investments
Assets
Investments, Adjusted Cost	4,598
Investments, Fair Value	$ 4,598
Fair Value Measurements Recurring \| Level 3 \| Convertible Preferred Stock Warrants Liability
Liabilities
Total liabilities measured at fair value		$ 683

Fair Value Measurements - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized gains or losses on sales of marketable securities	$ 0
Unrealized loss position for 12 months or greater on security	$ 0
Long-term marketable debt securities maturity period	13 months
Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative instrument, measurement input		0.002	0.002	0.002
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative instrument, measurement input		0.70	0.70	0.70
Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative instrument, measurement input		0.351	0.351	0.351
Long-term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt securities, aggregate cost basis	$ 3,000,000
Debt securities, fair value	$ 3,000,000

Fair Value Measurements - Schedule of Risk-free Interest Rate Based on U.S. Treasury Yield Curve Over Expected Term of Warrants (Details)	Jun. 24, 2019	Dec. 31, 2018	Dec. 31, 2017
Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Expected term (in years)	5 years 3 days	5 years 2 months 1 day	6 years 9 months
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Expected term (in years)	5 years 3 months 3 days	7 years	7 years 6 months
Volatility \| Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input	57.20	55.56	56.07
Volatility \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input	57.24	56.42	69.87
Risk-free Interest Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input	1.75
Risk-free Interest Rate \| Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input		2.58	1.97
Risk-free Interest Rate \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input		3.01	2.33

Fair Value Measurements - Summary of Changes in Fair Value of Level 3 Financial Instruments (Details) - Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Asset
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Balance	$ 0	$ 0	$ 0
Initial fair value of derivative asset		623
Change in fair value	0	(97)	0
Elimination as a result of debt extinguishment		(526)
Balance	0	0	0
Warrant Liability
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Balance	683	292	59
Issuance of convertible preferred stock warrants			169
Change in fair value	1,403	391	64
Reclassification of warrant liability to additional paid in capital on conversion	(2,086)
Balance	0	683	292
Derivative Liability
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Balance	0	671
Initial fair value of derivative liability			509
Change in fair value	0	(671)	162
Balance	$ 0	$ 0	$ 671

Borrowings - Summary of Amounts Outstanding Under Company's Financing Arrangements (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Debt Disclosure [Line Items]
Total principal payments due	$ 5,000
Less: Reduction in carrying value	(4)
Total amounts outstanding	4,996
Less: Current portion	(4,996)
Revolving Loan
Debt Disclosure [Line Items]
Total principal payments due	$ 5,000

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References + Details

Borrowings - Additional Information (Details) $ / shares in Units, $ in Thousands							1 Months Ended		12 Months Ended
	Aug. 14, 2019 USD ($)	Mar. 22, 2019 USD ($) $ / shares shares	Sep. 20, 2018 USD ($) $ / shares shares	Aug. 20, 2018 USD ($)	May 31, 2018 USD ($)	Jun. 29, 2017 USD ($) NumberofTime	Jun. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2014 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 20, 2019 shares	Dec. 31, 2017 USD ($)	Oct. 03, 2014 USD ($)
Debt Disclosure [Line Items]
Line of credit outstanding										$ 5,000
Warrant issued to purchase stock \| shares												188,643
Loss on debt extinguishment									$ (1,704)	(4,658)
Conversion of redeemable convertible preferred stock to common stock									89,404
Convertible notes, equity component										4,690
Convertible Notes
Debt Disclosure [Line Items]
Loss on debt extinguishment				$ (800)
Debt instrument, face value						$ 12,200
Debt instrument, interest rate						8.00%
Debt instrument, maturity date						Jun. 28, 2018
Debt instrument, convertible, threshold of proceeds from equity financing, qualified financing						$ 10,000
Debt instrument, convertible, conversion price. number of times multiplied on qualified financing \| NumberofTime						0.8
Debt instrument, percentage of outstanding principal amount to be repaid in cash in change of control						150.00%
Estimated fair value of compound derivative instrument						$ 500				0			$ 700
Debt instrument, carrying value, reduction accretion period, based on effective interest method						1 year
Debt instrument, effective interest rate						12.69%
Debt instrument, extended maturity date				Sep. 20, 2018
Conversion of redeemable convertible preferred stock to common stock				$ 13,400
Convertible notes, equity component				$ 800
Debt instrument, carrying value, accretion period, based on effective interest method				1 month
Interest expense, debt										900
Common Stock
Debt Disclosure [Line Items]
Conversion of redeemable convertible preferred stock to common stock									$ 2
Fair value of convertible notes, conversion of convertible securities \| shares									18,474,703
Revolving Loan
Debt Disclosure [Line Items]
Line of credit outstanding										5,000
Series C Redeemable Convertible Preferred Stock
Debt Disclosure [Line Items]
Conversion of redeemable convertible preferred stock to common stock			$ 13,400
Fair value of convertible notes, conversion of convertible securities \| shares			1,667,997
Debt Instrument, Convertible, Conversion Price \| $ / shares			$ 8.052
Series C Redeemable Convertible Preferred Stock \| Revolving Loan
Debt Disclosure [Line Items]
Warrant issued to purchase stock \| shares							62,096
Warrant exercise price per share \| $ / shares							$ 8.052
Term Loan
Debt Disclosure [Line Items]
Estimated fair value of warrants								$ 100
Debt Instrument, term								4 years
Term Loan \| Series B Redeemable Convertible Preferred Stock
Debt Disclosure [Line Items]
Warrant exercisable term								10 years
Warrant issued to purchase stock \| shares								22,489
Warrant exercise price per share \| $ / shares								$ 4.60
Convertible Notes
Debt Disclosure [Line Items]
Loss on debt extinguishment					$ (3,300)
Debt instrument, extended maturity date					Jun. 28, 2019
Conversion of redeemable convertible preferred stock to common stock					$ 13,100
Convertible notes, compound derivative asset					600
Convertible notes, equity component					$ 3,900
Debt instrument, carrying value, accretion period, based on effective interest method					1 year 1 month 6 days
Silicon Valley Bank \| Term Loan
Debt Disclosure [Line Items]
Line of credit facility, maximum borrowing capacity								$ 3,000
Line of credit outstanding														$ 2,400
Line of credit facility, frequency of payments									12 interest-only payments, followed by 36 equal monthly installments of principal, plus interest
TriplePoint Capital LLC
Debt Disclosure [Line Items]
Line of credit facility, maximum borrowing capacity		$ 20,000
Line of credit outstanding											$ 20,000
Line of credit facility, frequency of payments									36 equal monthly payments of principal, plus accrued interest, from April 1, 2020 through March 1, 2023
Estimated fair value of warrants		$ 600
Line of credit facility interest rate									15.23%
Interest expense									$ 1,000
Percentage of prepayment fee		1.00%
Percentage of principle payment amount		2.75%
Fees paid to lender		$ 300
Loss on debt extinguishment	$ (1,700)
TriplePoint Capital LLC \| Common Stock
Debt Disclosure [Line Items]
Warrant exercisable term		7 years
Warrant issued to purchase stock \| shares		65,502
Warrant exercise price per share \| $ / shares		$ 9.16
TriplePoint Capital LLC \| Maximum \| Option One
Debt Disclosure [Line Items]
Line of credit outstanding		$ 15,000
TriplePoint Capital LLC \| Minimum \| Option Two
Debt Disclosure [Line Items]
Line of credit outstanding		$ 15,000
TriplePoint Capital LLC \| Prime Rate \| Option One
Debt Disclosure [Line Items]
Interest rate, prime rate plus		5.00%
TriplePoint Capital LLC \| Prime Rate \| Option Two
Debt Disclosure [Line Items]
Interest rate, prime rate plus		6.50%
TriplePoint Capital LLC \| Revolving Loan
Debt Disclosure [Line Items]
Line of credit facility, maximum borrowing capacity							$ 10,000
Line of credit outstanding										5,000
Estimated fair value of warrants							$ 100
Debt Instrument, term							1 year 6 months
Line of credit facility interest rate							5.50%		19.22%
Line of credit facility maturity date									Dec. 31, 2018
Line of credit facility extended maturity date									Mar. 22, 2019
Line of credit facility, amount available to borrow										5,000
Interest expense										900
Accrued interest, related with accretion										$ 200
Repayments of amount outstanding		$ 5,100
TriplePoint Capital LLC \| Revolving Loan \| Prime Rate
Debt Disclosure [Line Items]
Interest rate, prime rate plus							6.75%
TriplePoint Capital LLC \| Series C Redeemable Convertible Preferred Stock \| Revolving Loan
Debt Disclosure [Line Items]
Warrant exercisable term							7 years
Warrant issued to purchase stock \| shares							62,096
Warrant exercise price per share \| $ / shares							$ 8.052

Leases - Additional Information (Details) $ in Thousands	1 Months Ended		12 Months Ended
Leases - Additional Information (Details) $ in Thousands	Aug. 31, 2019	Feb. 28, 2015 ft²	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2019 USD ($)	Jan. 01, 2019
Lessee Lease Description [Line Items]
Area of office space \| ft²		31,280
Lease expiration date		Nov. 30, 2020
Operating lease, existence of option to extend		true
Operating lease, option to extend			an option to extend the term for a period of three years
Operating lease option to extend term		3 years
Rent expense				$ 1,100
Operating lease right-of-use assets			$ 1,845
Lease liability			2,000
Operating lease cost			1,100
Cash paid for operating lease liabilities			$ 1,200
Weighted average remaining lease term			1 year 9 months 18 days
Weighted average incremental borrowing rate			7.30%
Laboratory and Office Space Lease
Lessee Lease Description [Line Items]
Incremental borrowing rate						8.00%
Co-located Data Center Space
Lessee Lease Description [Line Items]
Lease expiration date	Sep. 01, 2022
Operating lease, existence of option to extend	true
Operating lease, option to extend			an option to extend the term for a period of three years
Operating lease option to extend term	3 years
Incremental borrowing rate					6.60%
Operating lease right-of-use assets					$ 1,100
Lease liability					$ 1,100

Leases - Schedule of Future Minimum Lease Payments under ASC 840 (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 1,091
2020	1,030
Total future minimum lease payments	$ 2,121

Leases - Schedule of Future Minimum Lease Payments under ASC 842 (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Leases [Abstract]
2020	$ 1,408
2021	403
2022	319
Total future minimum lease payments	2,130
Less: Imputed interest	(130)
Present value of future minimum lease payments	2,000
Less: Current portion of operating lease liabilities	(1,361)
Operating lease liabilities - noncurrent	$ 639

Redeemable Convertible Preferred Stock - Summary of Redeemable Convertible Preferred Stock Outstanding (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Temporary Equity [Line Items]
Redeemable convertible preferred stock, Shares Authorized \| shares	75,238,150
Redeemable convertible preferred stock, Shares Issued \| shares	18,474,742
Redeemable convertible preferred stock, Shares Outstanding \| shares	18,474,742
Redeemable convertible preferred stock, Aggregate Liquidation Preference \| $	$ 89,784
Redeemable convertible preferred stock, Issuance Costs \| $	223
Redeemable convertible preferred stock, Net Carrying Value \| $	$ 89,404
Series A Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, Shares Authorized \| shares	31,250,000
Redeemable convertible preferred stock, Shares Issued \| shares	7,812,497
Redeemable convertible preferred stock, Shares Outstanding \| shares	7,812,497
Redeemable convertible preferred stock, Aggregate Liquidation Preference \| $	$ 20,500
Redeemable convertible preferred stock, Issuance Costs \| $	82
Redeemable convertible preferred stock, Net Carrying Value \| $	$ 20,261
Redeemable convertible preferred stock, Original Issuance Price Per Share \| $ / shares	$ 2.624
Series B Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, Shares Authorized \| shares	19,288,150
Redeemable convertible preferred stock, Shares Issued \| shares	4,799,548
Redeemable convertible preferred stock, Shares Outstanding \| shares	4,799,548
Redeemable convertible preferred stock, Aggregate Liquidation Preference \| $	$ 22,078
Redeemable convertible preferred stock, Issuance Costs \| $	31
Redeemable convertible preferred stock, Net Carrying Value \| $	$ 22,047
Redeemable convertible preferred stock, Original Issuance Price Per Share \| $ / shares	$ 4.600
Series C Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, Shares Authorized \| shares	24,700,000
Redeemable convertible preferred stock, Shares Issued \| shares	5,862,697
Redeemable convertible preferred stock, Shares Outstanding \| shares	5,862,697
Redeemable convertible preferred stock, Aggregate Liquidation Preference \| $	$ 47,206
Redeemable convertible preferred stock, Issuance Costs \| $	110
Redeemable convertible preferred stock, Net Carrying Value \| $	$ 47,096
Redeemable convertible preferred stock, Original Issuance Price Per Share \| $ / shares	$ 8.052

Redeemable Convertible Preferred Stock - Additional Information (Details) - shares		12 Months Ended
	Jun. 20, 2019	Dec. 31, 2019
Temporary Equity [Line Items]
Reverse stock split of common stock, description		four-for-one
IPO
Temporary Equity [Line Items]
Redeemable convertible preferred stock, terms of conversion		Immediately prior to the closing of the Company’s IPO, all shares of the Company’s then-outstanding Redeemable Convertible Preferred Stock, as shown in the table above, automatically converted on a one-for-one basis into an aggregate of 18,474,703 shares of common stock.
Fair value of convertible notes, conversion of convertible securities	18,474,703
Number of fractional shares issued	0
Number of issued common shares reduced upon conversion	39
Reverse stock split of common stock, description		The Reverse Stock Split was effected on a holder-by-holder basis with no fractional shares issued, which resulted in 39 fewer shares of common stock issued as compared to the amounts shown in the above table

- Definition

Specific terms relevant to convertibility. Includes class of preferred stock and number of shares convertible into, exercise (or conversion) price or rates, dates relevant to conversion timing and events relevant to conversion. Describe also any beneficial conversion features. where convertible preferred stock with a nondetachable conversion feature is in-the-money at commitment date. For contingently convertible preferred stock, discuss the circumstances of the contingency, including the events or changes in circumstance that would cause the contingency to be met and any of the significant features necessary to understand the conversion rights and the timing of those rights. Include also an events or changes in circumstance, if any, that could adjust or change the contingency, conversion price, or number of shares, including significant terms of those changes.

+ References + Details

Stock-Based Compensation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested shares subject to repurchase rights	0	262
Closing price of common stock	$ 10.90
Weighted-average grant date fair value of options granted	$ 8.00	$ 5.68	$ 2.44
Unrecognized stock-based compensation of unvested options	$ 9,600,000
Unrecognized stock-based compensation of unvested options, recognized over weighted-average period	2 years 9 months 18 days
Dividend yield	0.00%
Share-based compensation expense	$ 4,858,000	$ 1,317,000	$ 753,000
Expected volatility, minimum	56.20%	52.19%	56.05%
Expected volatility, maximum	63.08%	56.47%	65.78%
Risk-free interest rate, minimum	1.53%	2.62%	1.88%
Risk-free interest rate, maximum	2.52%	2.88%	2.10%
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years
Closing price of common stock	$ 10.90
Unrecognized stock-based compensation of unvested options, recognized over weighted-average period	2 years 10 months 24 days
Unrecognized stock-based compensation of unvested RSUs	$ 1,000,000
Performance Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 300,000	$ 0	$ 0
Outstanding shares with performance conditions vested	67,418	0	0
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average expected life	6 years 10 months 13 days	6 years 4 months 6 days	6 years 11 months 12 days
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average expected life	5 years	1 year 6 months	5 years 11 months 19 days
2011 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	4 years
Common stock available for issuance	4,474,057	4,647,839
2011 Plan \| Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	1 year
Vesting rate at the end of one year	25.00%
2011 Plan \| ISO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of exercise price granted to stockholder	10.00%
2011 Plan \| Options Granted as Merit Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	4 years
2011 Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted in years	10 years
2011 Plan \| Minimum \| ISO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of exercise price options granted	110.00%
2019 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock available for issuance	2,769,721
2019 Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted in years	10 years
2019 Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of exercise price options granted	100.00%
2019 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Common stock shares reserved for issuance	250,000
Percentage of purchase price of common stock	85.00%
Common stock shares purchased	77,684
Share-based compensation expense	$ 300,000
Expected volatility, minimum	59.10%
Expected volatility, maximum	59.90%
Risk-free interest rate, minimum	1.60%
Risk-free interest rate, maximum	2.10%
2019 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of earnings for purchase of common stock at discounted price	15.00%
Weighted-average expected life	6 months
2019 Employee Stock Purchase Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average expected life	4 months 13 days

Stock-Based Compensation - Summary of Stock Option Activity (Details) - 2011 Plan and 2019 Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding Options, Number of Shares, Beginning Balance	4,110,130	2,884,527	2,112,394
Outstanding Options, Number of Shares, granted	988,913	1,386,464	898,510
Outstanding Options, Number of Shares, exercised	(287,932)	(34,426)	(30,625)
Outstanding Options, Number of Shares, cancelled	(79,676)	(126,435)	(95,752)
Outstanding Options, Number of Shares, Ending Balance	4,731,435	4,110,130	2,884,527	2,112,394
Options vested and exercisable, Number of Shares	2,841,458
Outstanding Options, Weighted-Average Exercise Price, Beginning Balance	$ 3.16	$ 1.92	$ 1.76
Outstanding Options, Weighted-Average Exercise Price, granted	11.81	5.68	2.44
Outstanding Options, Weighted-Average Exercise Price, exercised	2.47	2.80	2.12
Outstanding Options, Weighted-Average Exercise Price, cancelled	6.61	2.96	3.20
Outstanding Options, Weighted-Average Exercise Price, Ending Balance	4.94	$ 3.16	$ 1.92	$ 1.76
Options vested and exercisable, Weighted-Average Exercise Price	$ 2.97
Outstanding Options, Weighted-Average Remaining Contractual Term (in years)	6 years 7 months 6 days	6 years 11 months 8 days	6 years 7 months 9 days	6 years 4 months 28 days
Options vested and exercisable, Weighted-Average Remaining Contractual Term (in years)	5 years 1 month 17 days
Outstanding Options, Aggregate Intrinsic Value	$ 29,730	$ 24,716	$ 5,860	$ 2,451
Outstanding Options, Aggregate Intrinsic Value, exercised		$ 96	$ 15
Options vested and exercisable, Aggregate Intrinsic Value	$ 22,858

Stock-Based Compensation - Summary of Restricted Stock Units Activity (Details) - Restricted Stock Units - 2019 Plan $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested Restricted Stock Units, Number of Shares, granted \| shares	120,000
Unvested Restricted Stock Units, Number of Shares, Ending Balance \| shares	120,000
Unvested Restricted Stock Units, Weighted-Average Grant Date Fair Value, granted \| $ / shares	$ 8.86
Unvested Restricted Stock Units, Weighted-Average Grant Date Fair Value, Ending Balance \| $ / shares	$ 8.86
Unvested Restricted Stock Units, Aggregate Fair Value \| $	$ 1,308

Stock-Based Compensation - Summary of Weighted-average Assumptions Used in Determination of Fair Value of Stock Options (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility, minimum	56.20%	52.19%	56.05%
Volatility, maximum	63.08%	56.47%	65.78%
Risk-free interest rate, minimum	1.53%	2.62%	1.88%
Risk-free interest rate, maximum	2.52%	2.88%	2.10%
Dividend yield	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years	1 year 6 months	5 years 11 months 19 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 10 months 13 days	6 years 4 months 6 days	6 years 11 months 12 days

Stock-Based Compensation - Summary of Stock-based Compensation Expense by Function (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 4,858	$ 1,317	$ 753
Costs of revenues
Stock Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	480	177	74
Research and development
Stock Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	903	429	225
Selling, general, and administrative
Stock Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 3,475	$ 711	$ 454

Redeemable Convertible Preferred Stock Warrants - Additional Information (Details) $ / shares in Units, $ in Millions	1 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2014 USD ($) $ / shares shares	Jun. 30, 2019 shares	Dec. 31, 2019 USD ($) shares	Jun. 20, 2019 shares	Dec. 31, 2018 USD ($)
Convertible Preferred Stock Warrants [Line Items]
Warrant issued to purchase stock					188,643
Fair values of convertible preferred stock warrants \| $						$ 0.7
Fair value transferred to additional paid-in capital \| $				$ 2.1
Common stock warrant exercised			22,489
Common stock issued for exercise of warrant			19,069
Common Stock
Convertible Preferred Stock Warrants [Line Items]
Warrant outstanding				62,096
Series B Redeemable Convertible Preferred Stock
Convertible Preferred Stock Warrants [Line Items]
Estimated fair value of convertible preferred stock \| $		$ 0.1
Contractual term		10 years
Series B Redeemable Convertible Preferred Stock \| Term Loan
Convertible Preferred Stock Warrants [Line Items]
Warrant issued to purchase stock		22,489
Warrant exercise price per share \| $ / shares		$ 4.60
Series B Redeemable Convertible Preferred Stock \| Risk-free Interest Rate
Convertible Preferred Stock Warrants [Line Items]
Warrants and rights outstanding, measurement input		2.52
Series B Redeemable Convertible Preferred Stock \| Volatility
Convertible Preferred Stock Warrants [Line Items]
Warrants and rights outstanding, measurement input		66.53
Series B Redeemable Convertible Preferred Stock \| Dividend Yield
Convertible Preferred Stock Warrants [Line Items]
Warrants and rights outstanding, measurement input		0
Series C Redeemable Convertible Preferred Stock \| Revolving Loan
Convertible Preferred Stock Warrants [Line Items]
Warrant issued to purchase stock	62,096
Warrant exercise price per share \| $ / shares	$ 8.052
Estimated fair value of convertible preferred stock \| $	$ 0.1
Contractual term	7 years
Series C Redeemable Convertible Preferred Stock \| Risk-free Interest Rate \| Revolving Loan
Convertible Preferred Stock Warrants [Line Items]
Warrants and rights outstanding, measurement input	1.97
Series C Redeemable Convertible Preferred Stock \| Volatility \| Revolving Loan
Convertible Preferred Stock Warrants [Line Items]
Warrants and rights outstanding, measurement input	64.33
Series C Redeemable Convertible Preferred Stock \| Dividend Yield \| Revolving Loan
Convertible Preferred Stock Warrants [Line Items]
Warrants and rights outstanding, measurement input	0

Common Stock Warrants - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 22, 2019	Dec. 31, 2019	Jun. 20, 2019	Aug. 31, 2011
Common Stock Warrants [Line Items]
Warrant issued to purchase stock			188,643
TriplePoint Capital LLC
Common Stock Warrants [Line Items]
Estimated fair value of warrants	$ 0.6
Series A Redeemable Convertible Preferred Stock
Common Stock Warrants [Line Items]
Estimated fair value of warrants				$ 0.1
Common Stock
Common Stock Warrants [Line Items]
Warrants outstanding		62,096
Common Stock \| TriplePoint Capital LLC
Common Stock Warrants [Line Items]
Warrant issued to purchase stock	65,502
Warrant exercise price per share	$ 9.16
Warrant exercisable term	7 years
Common Stock \| Series A Redeemable Convertible Preferred Stock
Common Stock Warrants [Line Items]
Warrant issued to purchase stock				188,643
Warrant exercise price per share				$ 0.04
Warrants outstanding		0

Net Loss per Share Attributable to Common Stockholders - Schedule of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net loss attributable to common stockholders									$ (25,084)	$ (19,886)	$ (23,598)
Denominator:
Weighted-average shares outstanding									18,011,955	3,063,516	3,035,791
Less: Weighted-average shares subject to repurchase									(485)	(359)	(4,155)
Weighted-average shares outstanding used in computing net loss per share attributable to common stockholders — basic and diluted									18,011,470	3,063,157	3,031,636
Net loss per share, basic and diluted	$ (0.21)	$ (0.22)	$ (0.89)	$ (1.84)	$ (1.16)	$ (1.19)	$ (2.39)	$ (1.76)	$ (1.39)	$ (6.49)	$ (7.78)

Net Loss per Share Attributable to Common Stockholders - Schedule of Dilutive Securities Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	5,054,438	22,858,362	21,546,865
Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	0	18,474,742	16,806,746
Conversion of Convertible Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	0	0	1,580,151
Common Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	127,598	188,643	188,643
Series B Preferred Stock Warrant
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	0	22,489	22,489
Series C Preferred Stock Warrant
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	0	62,096	62,096
Options To Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	4,731,435	4,110,130	2,884,527
Unvested Early Exercised Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	0	262	2,213
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	120,000	0	0
Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share	75,405	0	0

Net Loss per Share Attributable to Common Stockholders - Schedule of Dilutive Securities Excluded from Computation of Diluted Net Loss per Share (Parenthetical) (Details) - Conversion of Convertible Notes $ in Millions	Dec. 31, 2017 USD ($)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Debt instrument, face value	$ 12.2
Accrued but unpaid interest	$ 0.5

Income Taxes - Schedule of Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Domestic	$ (25,111)	$ (19,897)	$ (23,613)
Foreign	36	18	20
Loss before income taxes	$ (25,075)	$ (19,879)	$ (23,593)

Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
State	$ 1	$ 2	$ 1
Foreign	8	5	4
Total current	9	7	5
Provision for income taxes	$ 9	$ 7	$ 5

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Federal corporate tax rate	21.00%	21.00%	35.00%
Increase (Decrease) in valuation allowance on deferred tax assets	$ 7,600,000	$ 4,500,000
Expense, interest or penalties	0	0	$ 0
Accrued, interest or penalties	0	$ 0	$ 0
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 114,900,000
Net operating loss carryforwards, begins to expire	2031
Tax credit carryforward	$ 3,000,000
Tax credit carryforward, begins to expire	2031
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 72,200,000
Net operating loss carryforwards, begins to expire	2031
State \| Research
Income Tax Disclosure [Line Items]
Tax credit carryforward	$ 3,200,000
Maximum
Income Tax Disclosure [Line Items]
Federal corporate tax rate			35.00%

Income Taxes - Summary of Income Tax Provision Related to Continuing Operations Statutory Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal statutory rate	(21.00%)	(21.00%)	(35.00%)
Effect of:
State taxes	(8.00%)	(3.00%)	(7.00%)
Change in valuation allowance	28.00%	21.00%	(9.00%)
Rate impact due to tax reform			0.51
Research and development credit	(3.00%)	(3.00%)	(2.00%)
Debt extinguishment		4.00%
Other	4.00%	2.00%	2.00%
Effective tax rate	(0.00%)	(0.00%)	(0.00%)

Income Taxes - Components of Deferred Tax Assets for Federal and State Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 30,375	$ 22,441
Research and development credits	6,190	4,634
Deferred revenue	2,154	4,839
Accruals	784	460
Stock-based compensation	787	297
Inventory		42
Operating lease liabilities	574
Other intangibles	426	458
Other	114	3
Total gross deferred tax assets	41,404	33,174
Less: Valuation allowance	(40,000)	(32,423)
Net deferred tax assets	1,404	751
Deferred tax liabilities:
Property and equipment	(875)	(751)
Operating lease right-of-use assets	(529)
Net deferred tax liabilities	$ (1,404)	$ (751)

Income Taxes - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Beginning balance	$ 1,192	$ 917
Gross increase—tax provision in current period	389	275
Ending balance	$ 1,581	$ 1,192

Selected Quarterly Financial Information (Unaudited) - Summary of the Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 18,154	$ 17,153	$ 15,825	$ 14,075	$ 13,157	$ 11,654	$ 8,799	$ 4,164	$ 65,207	$ 37,774	$ 9,393
Gross profit	6,565	5,629	5,902	3,984	4,829	4,481	2,396	99
Net loss	$ (6,645)	$ (6,885)	$ (5,869)	$ (5,685)	$ (3,555)	$ (3,641)	$ (7,315)	$ (5,375)	$ (25,084)	$ (19,886)	$ (23,598)
Basic and diluted earnings per share	$ (0.21)	$ (0.22)	$ (0.89)	$ (1.84)	$ (1.16)	$ (1.19)	$ (2.39)	$ (1.76)	$ (1.39)	$ (6.49)	$ (7.78)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details