Natera (NTRA) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 01, 2020
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2020
Entity File Number	001-37478
Entity Registrant Name	Natera, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	01-0894487
Entity Address, Address Line One	201 Industrial Road, Suite 410
Entity Address, City or Town	San Carlos
Entity Address, State or Province	CA
Entity Address, Country	US
Entity Address, Postal Zip Code	94070
City Area Code	650
Local Phone Number	249-9090
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	NTRA
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		85,369,897
Entity Central Index Key	0001604821
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 209,351	$ 61,926
Restricted cash, current portion	178	55
Short-term investments	600,205	379,065
Accounts receivable, net of allowance of $3,080 in 2020 and $2,919 in 2019	70,674	53,351
Inventory	20,377	12,394
Prepaid expenses and other current assets, net	15,227	16,376
Total current assets	916,012	523,167
Property and equipment, net	28,249	23,283
Operating lease right-of-use assets	20,296	23,730
Other assets	12,156	12,476
Total assets	976,713	582,656
Current liabilities:
Accounts payable	9,250	8,604
Accrued compensation	22,450	16,088
Other accrued liabilities	62,893	49,043
Deferred revenue, current portion	51,227	56,016
Short-term debt financing	50,052	50,123
Total current liabilities	195,872	179,874
Long-term debt financing	199,959	73,656
Deferred revenue, long-term portion	23,128	23,808
Operating lease liabilities, long-term portion	21,444	26,297
Other long-term liabilities	310	310
Total liabilities	440,713	303,945
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock, $0.0001 par value: 750,000 shares authorized at both September 30, 2020 and December 31, 2019, respectively; 85,281 and 78,005 shares issued and outstanding at September 30, 2020 and December 31, 2019, respectively	9	8
Additional paid in capital	1,383,727	976,955
Accumulated deficit	(852,906)	(699,171)
Accumulated other comprehensive income	5,170	919
Total stockholders' equity	536,000	278,711
Total liabilities and stockholders' equity	$ 976,713	$ 582,656

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Condensed Consolidated Balance Sheets
Allowances on accounts receivable	$ 3,080	$ 2,919
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	750,000	750,000
Common stock, shares issued	85,281	78,005
Common stock, shares outstanding	85,281	78,005

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues
Total revenues	$ 98,143,000	$ 77,909,000	$ 278,627,000	$ 219,088,000
Cost and expenses
Research and development	26,421,000	12,796,000	67,651,000	36,355,000
Selling, general and administrative	75,678,000	56,715,000	209,547,000	147,589,000
Gain from disposal of business		(14,388,000)		(14,388,000)
Total cost and expenses	153,920,000	99,003,000	420,936,000	300,564,000
Loss from operations	(55,777,000)	(21,094,000)	(142,309,000)	(81,476,000)
Interest expense	(4,270,000)	(2,672,000)	(10,772,000)	(8,117,000)
Interest and other income, net	1,749,000	673,000	5,661,000	1,962,000
Loss on debt extinguishment			(5,848,000)
Loss before income taxes	(58,298,000)	(23,093,000)	(153,268,000)	(87,631,000)
Income tax expense	(25,000)	(44,000)	(63,000)	(2,013,000)
Net loss	(58,323,000)	(23,137,000)	(153,331,000)	(89,644,000)
Unrealized gain (loss) on available-for-sale securities, net of tax	(600,000)	63,000	4,251,000	1,410,000
Comprehensive loss	$ (58,923,000)	$ (23,074,000)	$ (149,080,000)	$ (88,234,000)
Net loss per share (Note 12):
Basic and diluted (in dollars per share)	$ (0.72)	$ (0.33)	$ (1.93)	$ (1.33)
Weighted-average number of shares used in computing basic and diluted net loss per share:
Basic and diluted (in shares)	80,908	70,456	79,430	67,198
Product
Revenues
Total revenues	$ 93,286,000	$ 66,936,000	$ 260,746,000	$ 195,399,000
Cost and expenses
Cost of revenues	46,873,000	40,138,000	131,124,000	123,125,000
Licensing and other
Revenues
Total revenues	4,857,000	10,973,000	17,881,000	23,689,000
Cost and expenses
Cost of revenues	$ 4,948,000	$ 3,742,000	$ 12,614,000	$ 7,883,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Total
Balance at Dec. 31, 2018	$ 7	$ 607,236	$ (552)	$ (574,529)	$ 32,162
Balance (in shares) at Dec. 31, 2018	62,083,000
Issuance of common stock upon exercise of stock options		10,416			10,416
Issuance of common stock upon exercise of stock options (in shares)	2,138,000
Issuance of common stock under employee stock purchase plan		2,147			2,147
Issuance of common stock under employee stock purchase plan (in shares)	132,000
Issuance of common stock for public offering, net		107,595			107,595
Issuance of common stock for public offering, net (in shares)	6,053,000
Issuance of common stock to Orbimed		506			506
Issuance of common stock to Orbimed (in shares)	25,000
Vesting of restricted stock (in shares)	419,000
Stock based compensation		20,102			20,102
Unrealized gain (loss) on available-for-sale securities/ ST investments			1,410		1,410
Cumulative-effect adjustment upon adoption		(185)		185
Net loss				(89,644)	(89,644)
Balance at Sep. 30, 2019	$ 7	747,817	858	(663,988)	84,694
Balance (in shares) at Sep. 30, 2019	70,850,000
Balance at Jun. 30, 2019	$ 7	733,137	795	(640,851)	93,088
Balance (in shares) at Jun. 30, 2019	70,035,000
Issuance of common stock upon exercise of stock options		4,433			4,433
Issuance of common stock upon exercise of stock options (in shares)	670,000
Vesting of restricted stock (in shares)	145,000
Stock based compensation		10,247			10,247
Unrealized gain (loss) on available-for-sale securities/ ST investments			63		63
Net loss				(23,137)	(23,137)
Balance at Sep. 30, 2019	$ 7	747,817	858	(663,988)	84,694
Balance (in shares) at Sep. 30, 2019	70,850,000
Balance at Dec. 31, 2019	$ 8	976,955	919	(699,171)	$ 278,711
Balance (in shares) at Dec. 31, 2019	78,005,000				78,005,000
Issuance of common stock upon exercise of stock options		15,782			$ 15,782
Issuance of common stock upon exercise of stock options (in shares)	1,534,000
Issuance of common stock under employee stock purchase plan		3,062			3,062
Issuance of common stock under employee stock purchase plan (in shares)	97,000
Equity component of Convertible Notes, net		82,873			82,873
Issuance of common stock for public offering, net	$ 1	270,649			$ 270,650
Issuance of common stock for public offering, net (in shares)	4,792,000
Issuance of common stock to Orbimed (in shares)					25,000
Vesting of restricted stock (in shares)	853,000
Stock based compensation		34,406			$ 34,406
Unrealized gain (loss) on available-for-sale securities/ ST investments			4,251		4,251
Cumulative-effect adjustment upon adoption				(404)	(404)
Net loss				(153,331)	(153,331)
Balance at Sep. 30, 2020	$ 9	1,383,727	5,170	(852,906)	$ 536,000
Balance (in shares) at Sep. 30, 2020	85,281,000				85,281,000
Balance at Jun. 30, 2020	$ 8	1,093,072	5,770	(794,583)	$ 304,267
Balance (in shares) at Jun. 30, 2020	79,717,000
Issuance of common stock upon exercise of stock options		4,974			4,974
Issuance of common stock upon exercise of stock options (in shares)	498,000
Issuance of common stock for public offering, net	$ 1	270,649			270,650
Issuance of common stock for public offering, net (in shares)	4,792,000
Vesting of restricted stock (in shares)	274,000
Stock based compensation		15,032			15,032
Unrealized gain (loss) on available-for-sale securities/ ST investments			(600)		(600)
Net loss				(58,323)	(58,323)
Balance at Sep. 30, 2020	$ 9	$ 1,383,727	$ 5,170	$ (852,906)	$ 536,000
Balance (in shares) at Sep. 30, 2020	85,281,000				85,281,000

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020
Operating activities
Net loss	$ (89,644)	$ (153,331)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	5,921	6,215
Premium amortization and discount accretion on investment securities	400	3,333
Stock-based compensation	20,102	34,406
Non-cash lease expense	5,807	5,819
Amortization of debt discount and issuance cost	336	149
Inventory reserve adjustments	719	(180)
Impairment of assets	1,310
Impairment of right-of-use assets	361
Provision for doubtful accounts	497
Other non-cash benefits	(22)	(135)
Gain on disposal of business	(14,388)
Provision for credit losses		1,445
Loss on Debt Extinguishment		5,848
Accretion of Convertible Note		4,514
Changes in operating assets and liabilities
Accounts receivable	(2,491)	(17,940)
Inventory	400	(7,803)
Prepaid expenses and other current assets	(9,321)	(7,288)
Other assets	(9,299)	97
Accounts payable	(5,194)	(1,613)
Accrued compensation	1,569	6,362
Other accrued liabilities	1,683	16,362
Deferred revenue	42,864	(5,470)
Net cash used in operating activities	(48,390)	(109,210)
Investing activities
Purchases of investments	(197,009)	(479,037)
Proceeds from sale of investments		11,500
Proceeds from maturity of investments	118,780	247,315
Net proceeds from disposal of business	9,675
Purchases of property and equipment, net	(2,554)	(12,073)
Net cash provided by investing activities	(71,108)	(232,295)
Financing activities
Proceeds from exercise of stock options	10,416	15,782
Proceeds from issuance of common stock under employee stock purchase plan	2,147	3,062
Proceeds from Convertible Note, net of issuance costs		278,316
Loan payment		(78,757)
Proceeds from public offering, net of issuance costs	107,595	270,650
Net cash provided by financing activities	120,158	489,053
Net increase in cash, cash equivalents and restricted cash	660	147,548
Cash, cash equivalents and restricted cash, beginning of period		61,981
Cash, cash equivalents and restricted cash, end of period	51,664	209,529
Supplemental disclosure of cash flow information:
Cash paid for interest	9,894	3,137
Supplemental non-cash investing and financing activities:
Obtaining right-of-use assets in exchange for lease liabilities	28,191
Purchases of property and equipment in accounts payable and accruals	$ 56	$ 2,814

Description of Business

Description of Business	9 Months Ended
	Sep. 30, 2020
Description of Business
Description of Business	1. Description of Business Natera, Inc. (the "Company") was formed in the state of California as Gene Security Network, LLC in November 2003 and incorporated in the state of Delaware in January 2007. The Company’s mission is to change the management of disease worldwide, focusing on women's health, oncology, and organ health. The Company operates a laboratory certified under the Clinical Laboratory Improvement Amendments ("CLIA") providing a host of preconception and prenatal genetic testing services. The Company determines its operating segments based on the way it organizes its business to make operating decisions and assess performance. The Company operates one segment, the development and commercialization of genetic testing services, applying its proprietary technology in the fields of women’s health, oncology and organ health. The Company also has a subsidiary that operates in the state of Texas. The Company's product offerings include its Panorama Non-Invasive Prenatal Test ("NIPT") that screens for chromosomal abnormalities of a fetus as well as in twin pregnancies, typically with a blood draw from the mother; Vistara (“Vistara”), a single-gene mutations screening test performed to identify single-gene disorders; Horizon Carrier Screening ("HCS") to determine carrier status for a large number of severe genetic diseases that could be passed on to the carrier’s children; Spectrum Pre-implantation Genetics (“Spectrum”) to evaluate embryos to identify chromosomal anomalies or inherited genetic conditions to improve the chances of a healthy pregnancy during an in vitro

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information. The unaudited interim condensed consolidated financial information includes only adjustments of a normal recurring nature necessary for a fair presentation of the results of operations, financial position, changes in stockholders’ equity, and cash flows. The results of operations for the three and nine months ended September 30, 2020, are not necessarily indicative of the results for the full year or the results for any future periods. The condensed consolidated balance sheet as of December 31, 2019 has been derived from audited financial statements at that date, these financial statements should be read in conjunction with the audited financial statements, and related notes for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 2, 2020. Liquidity Matters The Company has incurred net losses since its inception and anticipates net losses and negative operating cash flows for the near future. The Company had a net loss of $153.3 million for the nine months ended September 30, 2020 and an accumulated deficit of $852.9 million as of September 30, 2020. As of September 30, 2020, the Company had $209.5 million in cash, cash equivalents, and restricted cash, $600.2 million in marketable securities, $50.1 million of outstanding balance of the Credit Line (as defined in Note 10, Debt Debt The Company continues to develop and commercialize future products and, consequently, it will need to generate additional revenues to achieve future profitability and may need to raise additional equity or debt financing. If the Company raises additional funds by issuing equity securities, its stockholders will experience dilution. Additional debt financing, if available, may involve covenants restricting its operations or its ability to incur additional debt. Any additional debt financing or additional equity that the Company raises may contain terms that are not favorable to it or its stockholders and requires significant debt service payments, which diverts resources from other activities. Additional financing may not be available at all, or in amounts or on terms acceptable to the Company. If the Company is unable to obtain additional financing, it may be required to delay the development and commercialization of its products and significantly scale back its business and operations. In April 2019, the Company completed an underwritten equity offering and sold 6,052,631 shares of its common stock at a price of $19 per share to the public. Before offering expenses of $0.6 million, the Company received proceeds of $108.1 million net of the underwriting discount. In October 2019, the Company completed another underwritten equity offering and sold 6,571,428 shares of its common stock at a price of $35 per share to the public. Before offering expenses of $0.4 million, the Company received proceeds of $216.2 million net of the underwriting discount. In September 2020, the Company completed an additional underwritten equity offering and sold 4,791,665 shares of its common stock at a price of $60.00 per share to the public. Before offering expenses of $0.3 million, the Company received proceeds of $271.0 million net of the underwriting discount. Based on the Company’s current business plan, the Company believes that its existing cash and marketable securities will be sufficient to meet its anticipated cash requirements for at least 12 months after November 5, 2020. Principles of Consolidation ​ The accompanying condensed consolidated financial statements include all the accounts of the Company and its subsidiaries. The Company established a subsidiary that operates in the state of Texas to support the Company’s laboratory and operational functions. All intercompany balances and transactions have been eliminated. Use of Estimates The preparation of financial statements in accordance with generally accepted accounting principles (GAAP) in the United States requires management to make estimates and assumptions about future events that affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Significant items subject to such estimates include the allowance for doubtful accounts calculated based on the average selling price expected to be received from insurance payors, the operating right-of-use assets and the associated lease liabilities, deferred revenues associated with unsatisfied performance obligations, accrued liability for potential refund requests, the valuation of the Convertible Notes, stock-based compensation, the fair value of common stock, income tax uncertainties, and the expected consideration to be received from contracts with customers. These estimates and assumptions are based on management's best estimates and judgment. Management regularly evaluates its estimates and assumptions using historical experience and other factors, including contractual terms and statutory limits; however, actual results could differ from these estimates and could have an adverse effect on the Company's financial statements. Credit Losses ​ Trade accounts receivable and other receivables. ​ The following is a roll-forward of the allowances for credit losses related to trade accounts receivable and other receivables for the nine months ended September 30, 2020: ​ ​ ​ ​ ​ ​ September 30, ​ ​ 2020 ​ ​ ​ (in thousands) Beginning balance ​ $ 2,919 Cumulative-effect adjustment upon adoption of ASU 2016-13 ​ ​ 404 Provision for credit losses ​ ​ 1,445 Write-offs ​ ​ (457) Total ​ $ 4,311 ​ ​ ​ ​ ​ Available-for-sale debt securities. ​ Investments Investments consist primarily of debt securities such as U.S. Treasuries, U.S. agency and municipal bonds. Management determines the appropriate classification of securities at the time of purchase and re-evaluates such determination at each balance sheet date. The Company generally classifies its entire investment portfolio as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company classifies all investments as short-term, irrespective of maturity date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity. Risk and Uncertainties The Company is subject to risks and uncertainties as a result of the COVID-19 pandemic. The extent of the impact of the COVID-19 pandemic on the Company's business is highly uncertain and difficult to predict, and the full extent and duration of the impact of the COVID 19 pandemic on our business, our operations, and the global economy as a whole is not yet known. While the Company’s test volumes as well as overall average selling prices increased in Q3 2020 compared to Q2 2020, the Company cannot predict the potential nature, magnitude and duration of the effects of the COVID-19 pandemic on the macroeconomic environment. Financial instruments that potentially subject the Company to credit risk consist of cash, accounts receivable and investments. The Company limits its exposure to credit loss by placing its cash in financial institutions with high credit ratings. The Company's cash may consist of deposits held with banks that may at times exceed federally insured limits. The Company performs evaluations of the relative credit standing of these financial institutions and limits the amount of credit exposure with any one institution. The Company performs evaluations of financial conditions for insurance carriers, patients, clinics and laboratory partners and generally does not require collateral to support credit sales. For the three and nine months ended September 30, 2020, and 2019, there were no customers exceeding 10% of total revenues on an individual basis. As of September 30, 2020 and December 31, 2019, there were no customers with an outstanding balance exceeding 10% of net accounts receivable. ​ Accumulated Other Comprehensive Income (Loss) Comprehensive loss and its components encompass all changes in equity other than those with stockholders, and include net loss, unrealized gains and losses on available-for-sale marketable securities. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ September 30, ​ September 30, ​ 2020 ​ 2019 ​ 2020 ​ 2019 ​ (in thousands) ​ (in thousands) Beginning balance $ 5,770 ​ $ 795 ​ $ 919 ​ $ (552) Net unrealized gain (loss) on available-for-sale securities, net of tax ​ (600) ​ ​ 63 ​ ​ 4,251 ​ ​ 1,410 Ending balance $ 5,170 ​ $ 858 ​ $ 5,170 ​ $ 858 ​ Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) under its accounting standard codifications or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed below, the Company believes that the impact of accounting standards updates recently issued that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. Recently Adopted Accounting Pronouncements Fair Value Measurement In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement Goodwill - Internal-Use Software Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350 ‑ 40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract Credit Losses In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments Collaborative Arrangements Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 Income Taxes New Accounting Pronouncements Not Yet Adopted In March 2020, ASU 2020-04, Reference Rate Reform (Topic 848) In August 2020, ASU 2020-06, Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) In October 2020, ASU 2020-10, Codification Improvements comprehensive income. ASU 2010-10 is effective for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. Early application of the amendments is permitted for public business entities for any annual or interim period for which financial statements have not been issued. The Company is currently evaluating the impact of the adoption of this standard on its consolidated financial statements.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2020
Revenue Recognition
Revenue Recognition	­­ 3. Revenue Recognition The Company recognizes revenues when, or as, performance obligations in the contracts are satisfied, in the amount reflecting the expected consideration to be received from the goods or services transferred to the customers. Product Revenues ​ Product revenues are derived from contracts with insurance carriers, laboratory partners and patients in connection with sales of prenatal genetic tests. The Company enters into contracts with insurance carriers with primarily payment terms related to tests provided to the patients who have health insurance coverage. Insurance carriers are considered as third-party payers on behalf of the patients, and the patients are considered as the customers who receive genetic test services. Tests may be billed to insurance carriers, patients, or a combination of insurance carriers and patients. Further, the Company sells tests to a number of domestic and international laboratory partners and identifies the laboratory partners as customers provided that there is a test services agreement between the two parties. ​ A performance obligation represents a promise in a contract to transfer a distinct good or service to a customer, which represents a unit of accounting in accordance with ASC 606. A performance obligation is considered distinct from other obligations in a contract when it provides a benefit to the customer either on its own or together with other resources that are readily available to the customer and is separately identified in the contract. The Company considers a performance obligation satisfied once the Company has transferred control of a good or service to the customer, meaning the customer has the ability to use and obtain the benefit of the good or service. A portion of the consideration should be allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The Company evaluates its contracts with insurance carriers, laboratory partners and patients and identifies the performance obligations in those contracts, which are the delivery of the test results. ​ The total consideration which the Company expects to collect in exchange for the Company’s products is an estimate and may be fixed or variable. Consideration includes reimbursement from both patients and insurance carriers, adjusted for variable consideration related to disallowed cases, discounts, refunds and doubtful accounts, and is estimated using the expected value approach. For insurance carriers with similar reimbursement characteristics, the Company uses a portfolio of relevant historical data to estimate variable consideration and total collections for the Company’s products. The Company constrains the estimated variable consideration when it assesses it is probable that a significant reversal in the amount of cumulative revenue recognized may occur in future periods. The consideration expected from laboratory partners usually includes a fixed amount, but it can be variable depending on the volume of tests performed, and the Company determines the variable consideration using the expected value approach. For insurance carriers, laboratory partners and patients, the Company allocates the total consideration to a single performance obligation, which is the delivery of the test results to the customers. ​ When assessing the total consideration for insurance carriers and patients, a certain percentage of revenues is further constrained for estimated refunds. ​ The Company generally bills an insurance carrier, a laboratory partner or a patient upon delivery of test results. The Company also bills patients directly for out-of-pocket costs involving co-pays and deductibles that they are responsible for. Tests billed to insurance carriers and directly to patients usually take an average of nine two ​ Product revenue is recognized in an amount equal to the total consideration (as described above) at a point in time when the test results are delivered. The Company reserves certain amounts in other accrued liabilities on the balance sheet in anticipation of requests for refunds of payments previously made by insurance carriers, which are accounted for as reductions in product revenues in the statement of operations and comprehensive loss. During the three and nine months ended September 30, 2020, $1.1 million and $2.7 million were released from amounts previously held in reserves in other accrued liabilities, and $0.6 million and $1.9 million of such reserves were released during the three and nine months ended September 30, 2019, respectively. The release of amounts reserved were recognized as product revenue within that period. ​ Licensing and Other Revenues ​ The Company recognizes licensing revenues from its cloud-based distribution service offering, Constellation, by granting licenses to its licensees to use certain of the Company’s proprietary intellectual properties and cloud-based software and IVD kits. The Company also recognizes revenues from the Signatera research use only (“RUO”) offering, the Qiagen LLC, BGI Genomics Co., Ltd., and Foundation Medicine, Inc. agreements. Constellation The laboratory partners with which the Company enters into a licensing arrangement represent the licensees and are identified as customers. The licensees do not have the right to possess the Company’s software, but rather receive professional services through the cloud software. These arrangements often include: (i) the delivery of the professional services through the cloud software, (ii) the necessary support and training, and (iii) the IVD kits to be consumed as tests are processed. The Company does not consider the software as a service, the support and training as being distinct in the context of such arrangements, and therefore they are combined as a single performance obligation. The software, support and training are delivered simultaneously to the licensees over the term of the arrangement. The Company bills the majority of licensees, who process the tests in their laboratories, a fixed price for each test processed. Licensing revenues are recognized as the performance obligations are satisfied (i.e., upon the delivery of each test) and reported in licensing and other revenues in the statements of operations and comprehensive loss. Signatera The Company enters into agreements with pharmaceutical companies to utilize the Company’s Signatera tests typically to study new cancer treatments or to validate the outcomes of clinical trials for which the pharmaceutical companies are identified as customers. Such arrangements generally involve performing whole exome sequencing (“WES”) services and the testing of patient samples to detect cancer mutations using its Signatera test. Each test is billable to customers and the personalized cancer profile also makes each test distinct within the context of the contract as customers can exercise control over the test results upon delivery. The Company allocates the contract price to each test using the stand-alone selling price for each service and recognizes the test processing revenue as individual test results are delivered to customers. Qiagen circumstances. The Company provided to Qiagen standard indemnification protections, which is part of an assurance that the license meets the contract’s specifications and is not an obligation to provide goods or services. BGI Genomics ​ ​ ​ The Company is responsible for granting a license to specified intellectual property and performing certain development activities to customize its genetic testing assays for oncology and NIPT for use with BGI Genomics’ sequencing instruments and proprietary technology platform. Revenue associated with these performance obligations is recognized over time using the input method, based on costs incurred to perform the development services, since the level of costs incurred over time best reflect the transfer of development services. Revenue associated with the assay interpretation services will be recognized upon delivery of these services. Funds received in advance are recorded as deferred revenue and will be recognized as the related services are delivered. The initial transaction price was primarily comprised of license and milestone fees. The Company constrains the estimated variable consideration when it assesses it is probable that a significant reversal in the amount of cumulative revenue recognized may occur in future periods. Certain milestone and license fees were constrained and not included in the transaction price due to the uncertainties of research and development. The Company re-evaluates the transaction price, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The allocation of the transaction price was performed based on standalone selling prices, which are based on estimated amounts that the Company would charge for a performance obligation if it were sold separately. In accordance with ASC 340-40, any incremental costs incurred to obtain a contract with a customer are required to be capitalized and amortized over the period in which the goods and services are transferred to the customer. The Company has elected to apply a practical expedient under ASC 340-40 to recognize the incremental costs of obtaining a contract as an expense when incurred provided that the amortization period of such costs, if capitalized, is one year or less. The incremental costs incurred in connection with the BGI Genomics arrangement is not material on an accumulated basis and therefore will not be capitalized on the balance sheet but will be expensed as incurred. Foundation Medicine, Inc. In August 2019, the Company entered into a License and Collaboration Agreement (“the Foundation Medicine Agreement”) with Foundation Medicine, Inc. (“Foundation Medicine”) to develop and commercialize personalized circulating tumor DNA monitoring assays, for use by biopharmaceutical and clinical customers who order Foundation Medicine’s FoundationOne CDx. The agreement has an initial term of five years, expiring in August 2024, with automatic renewals thereafter for successive one-year terms, unless the agreement is earlier terminated in accordance with its terms. Natera and Foundation Medicine will share the revenues generated from both biopharmaceutical and clinical customers in accordance with the terms of the agreement. The agreement provides for approximately $13.3 million in upfront licensing fees and prepaid revenues payable to the Company, and up to approximately $32.0 million in minimum annual payments and payments tied to the Company’s achievement of certain developmental, regulatory, and commercial milestones. As of December 31, 2019, the Company received $16.3 million of these amounts, of which $3.0 million was for achieving certain milestones, and $13.3 million was for licensing fees and prepaid revenue. No additional payments have been received in the nine months ending September 30, 2020. ​ Pursuant to the agreement, the Company will provide development services in conjunction with granting the use of the Company’s intellectual property. Following completion of those development services, the Company will provide assay testing services over the term of the agreement. The Company has concluded that the license is not a distinct performance obligation as it is highly interrelated and interdependent with the related development services. Therefore, license and related development services represent a single performance obligation. ​ The Company is responsible for providing the technology license and certain development services that are required to customize its proprietary Signatera test to work with Foundation Medicine’s FoundationOne CDx. The intellectual property has been licensed to Foundation Medicine for the customized test. In addition, the Company is responsible for delivering clinical study plans in order to demonstrate efficacy of the customized test. Revenues associated with each of the performance obligations are recognized over time using the input method, based on costs incurred to perform the development services, since the level of costs incurred over time best reflect the transfer of development services. Revenue associated with the assay testing services will be recognized upon delivery of these services. Funds received in advance are recorded as deferred revenue and will be recognized as the related services are delivered. ​ The initial transaction price was primarily comprised of license and milestone fees. The Company constrains the estimated variable consideration when it assesses it is probable that a significant reversal in the amount of cumulative revenue recognized may occur in future periods. Certain milestone fees were constrained and not included in the transaction price due to the uncertainties of research and development. The Company re-evaluates the transaction price, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The allocation of the transaction price was performed based on standalone selling prices, which are based on estimated amounts that the Company would charge for a performance obligation if it were sold separately. ​ In accordance with ASC 340-40, any incremental costs incurred to obtain a contract with a customer are required to be capitalized and amortized over the period in which the goods and services are transferred to the customer. The Company has elected to apply a practical expedient under ASC 340-40 to recognize the incremental costs of obtaining a contract as an expense when incurred provided that the amortization period of such costs, if capitalized, is one year or less. Disaggregation of Revenues ​ The Company measures its performance results primarily based on revenues recognized from the three categories described below. The following table shows disaggregation of revenues by payer types: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ September 30, ​ September 30, ​ ​ 2020 ​ 2019 ​ 2020 ​ 2019 (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Insurance carriers ​ $ 78,004 ​ $ 51,801 ​ $ 216,305 ​ $ 152,779 Laboratory and other partners ​ ​ 13,701 ​ ​ 16,938 ​ ​ 42,426 ​ ​ 42,093 Patients ​ ​ 6,438 ​ ​ 9,170 ​ ​ 19,896 ​ ​ 24,216 Total revenues ​ $ 98,143 ​ $ 77,909 ​ $ 278,627 ​ $ 219,088 ​ The following table presents total revenues by geographic area based on the location of the Company’s payers: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ September 30, ​ September 30, ​ 2020 2019 2020 ​ 2019 (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ United States $ 93,511 ​ $ 64,839 ​ $ 260,999 ​ $ 187,515 ​ Americas, excluding U.S. ​ 1,081 ​ ​ 806 ​ ​ 2,584 ​ ​ 2,391 ​ Europe, Middle East, India, Africa ​ 3,524 ​ ​ 3,497 ​ ​ 10,584 ​ ​ 11,819 ​ Asia Pacific and Other ​ 27 ​ ​ 8,767 ​ ​ 4,460 ​ ​ 17,363 ​ Total revenues $ 98,143 ​ $ 77,909 ​ $ 278,627 ​ $ 219,088 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Balance at ​ ​ September 30, ​ December 31, (in thousands) ​ 2020 ​ 2019 Assets: ​ ​ ​ ​ ​ ​ Accounts receivable ​ $ 70,674 ​ $ 53,351 Liabilities: ​ ​ ​ ​ ​ ​ Deferred revenue, current portion ​ $ 51,227 ​ $ 56,016 Deferred revenue, long-term portion ​ ​ 23,128 ​ ​ 23,808 Total deferred revenues ​ $ 74,355 ​ $ 79,824 ​ ​ ​ ​ ​ ​ ​ ​ Deferred ​ ​ Revenues ​ ​ (in thousands) Balance at December 31, 2019 ​ $ 79,824 Increase in deferred revenues ​ ​ 1,579 Reclasses from deferred revenues to other short-term liabilities ​ ​ (801) Revenue recognized during the period that was included in ​ ​ (5,290) Revenue recognized from performance obligations satisfied ​ ​ (957) Balance at September 30, 2020 ​ $ 74,355 ​

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Fair Value Measurements
Fair Value Measurements	4. Fair Value Measurements The Company's financial assets and liabilities carried at fair value are comprised of investment assets that include money market and investments. The fair value accounting guidance requires that assets and liabilities be carried at fair value and classified in one of the following three categories: Level I: Quoted prices in active markets for identical assets and liabilities that the Company has the ability to access. Level II: Observable market-based inputs or unobservable inputs that are corroborated by market data, such as quoted prices, interest rates, and yield curves. Level III: Inputs that are unobservable data points that are not corroborated by market data. This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. Assets and Liabilities That Are Measured at Fair Value on a Recurring Basis ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 ​ December 31, 2019 ​ Level I Level II Level III Total Level I Level II Level III Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Financial Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market deposits ​ $ 178,894 $ — $ — ​ $ 178,894 ​ $ 22,477 $ — $ — ​ $ 22,477 U.S. Treasury securities ​ ​ 530,808 ​ — ​ — ​ ​ 530,808 ​ ​ 293,157 ​ — ​ — ​ ​ 293,157 Municipal securities ​ ​ — ​ 69,397 ​ — ​ ​ 69,397 ​ ​ — ​ 85,908 ​ — ​ ​ 85,908 Total financial assets ​ $ 709,702 $ 69,397 $ — ​ $ 779,099 ​ $ 315,634 $ 85,908 $ — ​ $ 401,542 ​

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2020
Financial Instruments
Financial Instruments	5. Financial Instruments The Company elected to invest a portion of its cash assets in conservative, income earning, and liquid investments. Cash equivalents and investments, all of which are classified as available-for-sale securities, consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 ​ December 31, 2019 ​ Amortized Gross Gross Estimated Fair Value Amortized Gross Gross Estimated Fair Value ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Money market deposits ​ $ 178,894 ​ $ — ​ $ — ​ $ 178,894 ​ $ 22,477 ​ $ — ​ $ — ​ $ 22,477 U.S. Treasury securities (1) ​ 526,643 ​ ​ 4,173 ​ ​ (8) ​ 530,808 ​ 292,506 ​ 731 ​ (80) ​ 293,157 Municipal securities ​ ​ 68,411 ​ ​ 997 ​ ​ (11) ​ ​ 69,397 ​ ​ 85,638 ​ ​ 277 ​ ​ (7) ​ ​ 85,908 Total ​ $ 773,948 ​ $ 5,170 ​ $ (19) ​ $ 779,099 ​ $ 400,621 ​ $ 1,008 ​ $ (87) ​ $ 401,542 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents (2) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 178,894 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 22,477 Short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 600,205 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 379,065 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 779,099 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 401,542 ​ (1) Per the Company’s investment policy, all U.S. Treasury securities are classified as short-term investments irrespective of holding period. (2) Cash equivalents includes cash sweep accounts and U.S. Treasury money market mutual funds. ​ The Company invests in U.S. Treasuries, U.S. agency and high quality municipal bonds which mature at par value and are all paying their coupons on schedule. The Company has therefore concluded there is currently no In accordance with the adoption of ASU 2016-13 (Topic 326), the Company has assessed the unrealized loss position for available-for-sale debt securities for which an allowance for credit losses has not been recorded. The fair value for investment securities at an unrealized loss position as of September 30, 2020 was $122.9 million. The aggregate amount of unrealized losses of these securities were not significant, and the impact of the securities in a continuous loss position to the condensed consolidated statements of operations and comprehensive loss were not material as of September 30, 2020. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 ​ ​ Amortized ​ Fair ​ ​ (in thousands) Less than or equal to one year ​ $ 338,583 ​ $ 339,655 Greater than one year but less than five years ​ ​ 256,464 ​ ​ 260,550 Total ​ $ 595,047 ​ $ 600,205 ​

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2020
Balance Sheet Components
Balance Sheet Components	6. Balance Sheet Components ​ Property and Equipment, net ​ The Company’s property and equipment consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ Useful Life 2020 2019 ​ ​ (in thousands) Machinery and equipment 3 -5 $ 47,158 ​ $ 36,414 Furniture and fixtures 3 years ​ 1,376 ​ 1,376 Computer equipment 3 years ​ 2,025 ​ 1,828 Capitalized software held for internal use 3 years ​ 7,079 ​ ​ 5,917 Leasehold improvements Lesser of useful life or lease term ​ 14,586 ​ 11,556 Construction-in-process ​ ​ 3,692 ​ 7,716 ​ ​ ​ 75,916 ​ 64,807 Less: Accumulated depreciation and amortization ​ ​ (47,667) ​ (41,524) Total Property and Equipment, net ​ $ 28,249 ​ $ 23,283 ​ During the nine months ended September 30, 2020, the increase in net property in equipment was due to purchases of new equipment for our laboratories located in California and Texas to expand testing capabilities, offset by depreciation expense of $6.2 million recorded in the nine months ended September 30, 2020. The Company did not incur an impairment charge during the nine months ended September 30, 2020. ​ Other Assets ​ In August 2017, the Company entered into the 2017 Term Loan with OrbiMed (as described in Note 10, Debt Debt ​ As of September 30, 2020, other assets also included long-term advances to BGI Genomics of $10.0 million for future sequencing equipment and services. Furthermore, other assets include additional consideration estimated at $1.5 million net of allowance in connection with the sale of Evercord, which represent the amount the Company is entitled to receive from the buyer as a percentage of collections on the transferred accounts receivable as part of the sale (i.e., receivables from third-party buyer). The consideration decreased from $4.7 million as of December 31, 2019 due to $2.0 million of net collections from the buyer and $1.2 million credit loss expense on the additional consideration. The credit loss expense was determined based on a recent collectability assessment of the accounts receivables transferred to the buyer on the disposal date. ​ Accrued Compensation ​ The Company’s accrued compensation consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ 2020 2019 ​ (in thousands) Accrued paid time off $ 2,153 ​ $ 1,850 Accrued commissions 7,376 ​ 5,767 Accrued bonuses 6,964 ​ 5,710 Other accrued compensation 5,957 ​ 2,761 Total accrued compensation $ 22,450 ​ $ 16,088 ​ Other Accrued Liabilities ​ The Company’s other accrued liabilities consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ 2020 2019 ​ (in thousands) Reserves for refunds to insurance carriers $ 13,322 ​ $ 9,410 Accrued charges for third-party testing ​ 5,668 ​ ​ 8,408 Testing and laboratory materials from suppliers ​ 8,618 ​ ​ 4,301 Marketing and corporate affairs ​ 3,235 ​ ​ 2,957 Legal, audit and consulting fees 4,666 ​ 2,873 Accrued shipping charges ​ 745 ​ ​ 305 Sales tax payable ​ 1,405 ​ ​ 1,691 Accrued specimen service fees ​ 2,247 ​ ​ 2,269 Clinical trials and studies ​ 1,828 ​ ​ 1,092 Operating lease liabilities, current portion ​ 6,380 ​ ​ 5,739 Fixed asset purchases ​ 1,959 ​ ​ 1,482 Other accrued interest ​ 2,965 ​ ​ — Other accrued expenses 9,855 ​ ​ 8,516 Total other accrued liabilities $ 62,893 ​ $ 49,043 ​ Reserves for refunds to insurance carriers include overpayments from and amounts to be refunded to insurance carriers, and additional amounts that the Company estimates for potential refund requests during the period. When the Company releases these previously accrued amounts, they are recognized as product revenues in the statements of operations and comprehensive loss. ​ The following table summarizes the reserve balance and activities for refunds to insurance carriers for the nine months ended September 30, 2020: ​ ​ ​ ​ ​ ​ ​ ​ September 30, September 30, ​ 2020 2019 ​ (in thousands) Beginning balance $ 9,410 ​ ​ 10,012 Additional reserves 11,912 ​ 7,193 Reserves released and actual refunds (8,000) ​ (8,513) Ending balance $ 13,322 ​ $ 8,692 ​ ​ ​ ​ ​ ​ Released into revenue during the nine months ended $ 2,756 ​ $ 1,895 ​ ​ ​ ​ ​ ​ ​

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases
Leases	7. Leases ​ Operating Leases ​ ​ ​ ​ ​ September 30, ​ 2020 ​ ​ (in thousands) Operating lease liabilities, current portion included in other accrued liabilities $ 6,380 Operating lease liabilities, long-term portion ​ 21,444 Total operating lease liabilities $ 27,824 ​ The present value of the future annual minimum lease payments under all non-cancellable operating leases as of September 30, 2020 are as follows: ​ ​ ​ ​ ​ Operating Leases ​ (in thousands) Year ending December 31: ​ ​ 2020 (remaining 3 months) $ 2,244 2021 ​ 9,067 2022 ​ 9,319 2023 ​ 7,797 2024 ​ 2,400 2025 and thereafter ​ 4,730 ​ ​ 35,557 Less: imputed interest ​ (7,733) Operating lease liabilities $ 27,824 ​

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies
Commitments and Contingencies	8. Commitments and Contingencies Legal Proceedings From time to time, the Company is involved in disputes, litigation, and other legal actions, including those with respect to intellectual property, employment, testing and other matters. Such actions may include allegations of negligence, products/professional liability or other similar legal claims, and could involve claims for substantial compensatory and/or punitive damages or claims for indeterminate amounts of damages. The Company is aggressively defending and/or prosecuting its current litigation matters, but cannot provide any assurance as to the ultimate outcome or that an adverse resolution would not have a material adverse effect on its financial condition and results of operations. There are many uncertainties associated with any litigation and these actions or other third party claims against the Company, or by the Company against third parties, may cause the Company to incur costly litigation and/or substantial settlement charges. In addition, the resolution of any intellectual property litigation may require the Company to make royalty payments, which could adversely affect gross margins in future periods. If this were to occur, the Company's business, financial condition, results of operations, and cash flows could be adversely affected. The Company assesses legal contingencies to determine the degree of probability and range of possible loss for potential accrual in its financial statements. When evaluating legal contingencies, the Company may be unable to provide a meaningful estimate due to a number of factors, including the procedural status of the matter in question, the presence of complex or novel legal theories, and/or the ongoing discovery and development of information important to the matters. In addition, damage amounts claimed in litigation against it may be unsupported, exaggerated or unrelated to possible outcomes, and as such are not meaningful indicators of its potential liability. During the periods presented, the Company has not recorded any accrual for loss contingencies associated with such legal proceedings, determined that an unfavorable outcome is probable or reasonably possible, or determined that the amount or range of any possible loss is reasonably estimable. Illumina Litigation. In March 2018, Illumina, Inc., or Illumina, filed a lawsuit (the ’831 lawsuit) against the Company in the United States District Court for the Northern District of California, alleging that the Company’s Panorama test infringes certain claims of U.S. Patent No. 9,493,831 (the ’831 patent) and seeking, among other relief, damages or other monetary relief including costs and pre- and post-judgment interest, treble damages, injunctive relief, attorneys’ fees and costs. In August 2018, the Company filed a counterclaim against Illumina, alleging that certain of Illumina’s NIPT tests infringe on the Company’s U.S. Patent No. 8,682,592 (the ’592 patent) and seeking, among other relief, damages or other monetary relief including costs and pre- and post-judgment interest, treble damages, injunctive relief, attorneys’ fees and costs (together with the ‘831 lawsuit, the “Illumina Litigation”). On June 13, 2019, Illumina filed a petition for inter partes inter partes CareDx Litigation Matters. On March 26, 2019, CareDx, Inc., or CareDx, filed suit against the Company in the United States District Court for the District of Delaware (“CareDx’s Patent Case”). The suit alleges that the Company infringed two patents, 9,845,497 and 8,703,652. The complaint seeks unspecified damages and injunctive relief. On March 23, 2020, CareDx additionally alleged in an amended complaint that the Company infringed U.S. Patent No. 10,329,607. The Company has also alleged that CareDx infringes Natera’s U.S. Patent Nos. 10,526,658 and 10,597,724, seeking unspecified damages and injunctive relief. On June 12, 2020, Natera filed a motion for early summary judgment of invalidity against all three of CareDx’s patent assertions. The motion has been fully briefed and is awaiting a decision from the Court. ​ In addition, on April 10, 2019, CareDx filed suit against the Company in the United States District Court for the District of Delaware, alleging false advertising, trademark disparagement, unfair competition, and unfair or deceptive trade practices based on statements describing studies that concern the Company’s technology and CareDx’s technology (“CareDx’s Advertising Case”). The complaint seeks unspecified damages and injunctive relief. On May 30, 2019, the Company filed a motion to dismiss the entirety of CareDx’s Advertising Case for failure to state a claim. On February 7, 2020, CareDx filed an amended complaint withdrawing its trademark disparagement claim. On February 18, 2020, the Company filed a counterclaim against CareDx in the United States District Court for the District of Delaware, alleging false advertising, unfair competition and deceptive trade practices and seeking unspecified damages and injunctive relief. Other Litigation Matters. On January 27, 2020, the Company filed suit against ArcherDX, Inc., or ArcherDX, in the United States District Court for the District of Delaware, alleging that certain ArcherDX DNA oncology products infringe Natera’s U.S. Patent No. 10,538,814. On April 15, 2020, Natera filed an amended complaint alleging additional ArcherDX DNA and RNA oncology products infringe Natera’s U.S. Patent Nos. 10,557,172; 10,597,708; and 10,590,482. The amended complaint seeks monetary damages and injunctive relief. On August 6, 2020, the Company filed an additional suit against ArcherDX in the United States District Court for the District of Delaware, alleging that certain ArcherDX DNA oncology products infringe Natera’s U.S. Patent No. 10,731,220 and seeking monetary damages and injunctive relief. On June 4, 2020, ArcherDX filed a motion to dismiss aspects of the Company’s case, including to invalidate several of Natera’s asserted patents. That motion was denied in its entirety on October 2, 2020. On June 17, 2020, the Company filed suit against Progenity, Inc., or Progenity, in the United States District Court for the Western District of Texas, alleging that Progenity’s NIPT test infringes Natera’s U.S. Patent Numbers 9,228,234; 9,424,392; 10,227,652; 10,240,202; 10,266,893; and 10,522,242 (the “Natera Patents”). The complaint seeks treble damages and injunctive relief. The Company filed a second suit against Progenity in the United States District Court for the Northern District of Texas on June 19, 2020, alleging that Progenity’s NIPT test infringes the Natera Patents, and seeking treble damages and injunctive relief. On or about July 2, 2020, Progenity filed suit against the Company in the United States District Court for the Southern District of California, seeking declaratory judgment of non-infringement of the Natera Patents. On October 6, 2020, the Company filed suit against Genosity Inc. (“Genosity”) in the United States District Court for the District of Delaware, alleging that various Genosity products infringe Natera’s U.S. Patent No. 10,732,220. The complaint seeks unspecified monetary damages and injunctive relief. ​ On June 1, 2020, a suit was filed against the Company in the United States District Court for the Western District of Texas by Ravgen, Inc., alleging infringement of U.S. Patent Nos. 7,727,720 and 7,332,277. The complaint seeks monetary damages and injunctive relief. On or about August 13, 2019, a suit was filed against the Company in the Circuit Court of Cook County, Illinois by a patient alleging claims relating to a discordant test result and seeking monetary damages. On March 15, 2019, a purported class action lawsuit was filed against the Company in the United States District Court for the Northern District of California, alleging that the plaintiff received an unauthorized text message to her cellular telephone in violation of the Telephone Consumer Protection Act. Among other relief, the complaint sought statutory and other damages, injunctive relief, attorneys’ fees, and costs. On June 18, 2019, the Company filed a motion to dismiss, which was denied. An amended complaint was filed on April 23, 2020. The case was dismissed by stipulation of the parties effective November 2, 2020. ​ Director and Officer Indemnifications As permitted under Delaware law, and as set forth in the Company’s Certificate of Incorporation and its Bylaws, the Company indemnifies its directors, executive officers, other officers, employees and other agents for certain events or occurrences that may arise while in such capacity. The maximum potential amount of future payments the Company could be required to make under this indemnification is unlimited; however, the Company has insurance policies that may limit its exposure and may enable it to recover a portion of any future amounts paid. Assuming the applicability of coverage, the willingness of the insurer to assume coverage, and subject to certain retention, loss limits and other policy provisions, the Company believes any obligations under this indemnification would not be material, other than an initial $1.5 million for securities related claims and $0.3 million for commercial general liability claims. However, no assurances can be given that the covering insurers will not attempt to dispute the validity, applicability, or amount of coverage without expensive litigation against these insurers, in which case the Company may incur substantial liabilities as a result of these indemnification obligations. Third-Party Payer Reimbursement Audits From time to time, the Company receives recoupment requests from third-party payers for alleged overpayments. The Company disagrees with the contentions of pending requests and/or has recorded an estimated reserve for the alleged overpayments. Contractual Commitments The following table sets forth the material contractual commitments as of September 30, 2020 with a remaining term of at least one year: ​ ​ ​ ​ ​ ​ Party Commitments ​ Expiry Date ​ ​ (in thousands) ​ ​ Laboratory instruments supplier $ 4,549 ​ December 2021 Material supplier ​ 13,633 ​ May 2030 Application service providers ​ 10,711 ​ Jan-21 - Dec-24 Gene sequencing reagents and kits provider ​ 473 ​ April 2021 Other material suppliers ​ 10,960 ​ Various Total $ 40,326 ​ ​ ​

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2020
Stock-Based Compensation
Stock-Based Compensation	9. Stock-Based Compensation 2015 Equity Incentive Plan In June 2015, the Board adopted, and the Company’s stockholders approved, the Company’s 2015 Equity Incentive Plan (the “2015 Plan”), which, by its terms, took effect as of the Company’s IPO on July 2, 2015. The 2015 Plan replaced the Company’s 2007 Stock Plan (the “2007 Plan”). No further awards have been granted under the 2007 Plan after July 1, 2015. However, any remaining awards that were outstanding under the 2007 Plan will continue to be governed by the terms of that plan. The Company initially reserved 3,451,495 shares of its common stock for issuance under the 2015 Plan; in addition, the Company authorized the reservation of up to 9,890,310 shares of common stock to cover shares reserved but unissued under the 2007 Plan and shares subject to outstanding awards under the 2007 Plan that expire or lapse unexercised or shares issued under the 2007 Plan that are subsequently reacquired by the Company. Performance-based Awards ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Period Granted ​ Options Granted ​ RSUs Granted ​ Options Vested ​ RSUs Vested ​ Milestone ​ Valuation Method (in thousands) Q1 2019 ​ 200 ​ 300 ​ 118 ​ 184 ​ (1) ​ Monte-Carlo Simulation Q2 2019 ​ — ​ 188 ​ — ​ — ​ (2) ​ Fair Market Value Q3 2019 ​ — ​ 50 ​ — ​ 25 ​ (1) ​ Monte-Carlo Simulation Q1 2020 ​ 150 ​ 300 ​ 38 ​ 131 ​ (1) ​ Monte-Carlo Simulation Q1 2020 ​ — ​ 436 ​ — ​ 4 ​ (3) ​ Fair Market Value Q1 2020 ​ 129 ​ — ​ — ​ — ​ (3) ​ Black-Scholes-Merton Q2 2020 ​ — ​ 21 ​ — ​ — ​ (3) ​ Fair Market Value Q3 2020 ​ 10 ​ — ​ 7 ​ — ​ (4) ​ Black-Scholes-Merton Q3 2020 ​ — ​ 27 ​ — ​ 3 ​ (3) ​ Fair Market Value ________________________________ (1) The awards will vest based on the achievement of certain values of the Company’s common stock at multiple thresholds within certain periods and are contingent upon the completion of requisite service through the date of such vesting. ​ (2) The vesting of the awards will be triggered after the end of the achievement milestone, as measured by the Company. ​ (3) The awards will vest based on achievement of certain revenue target and are contingent upon the completion of requisite service through the date of such vesting. ​ (4) The awards will vest based on a change of coverage. ​ The Company has recognized $6.6 million and $11.8 million in stock-based compensation for performance-based awards for the three and nine months ended September 30, 2020, respectively. The Company has recognized $0.4 million and $0.6 million in stock-based compensation for performance-based awards for the three and nine months ended September 30, 2019, respectively. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2020 Risk-free interest rate ​ 0.61 % — 1.64 % Expected dividend yield ​ ​ ​ ​ 0.00 % Expected volatility ​ 55 % — 65 % Expected term (years) ​ 5.25 ​ — 7.25 ​ ​ Employee Stock Purchase Plan There have not been any changes to the Company’s 2015 Natera, Inc. Employee Stock Purchase Plan (the “ESPP”) as disclosed in Form 10-K for the fiscal year ended December 31, 2019. The Company has made 893,548 shares available for issuance under the Plan, a number that is automatically increased by the least of (i) 1% of the total number of shares of common stock actually issued and outstanding on the last business day of the prior fiscal year, (ii) 880,000 shares of common stock (subject to certain adjustments pursuant to Subsection (c) below), or (iii) a number of shares of common stock determined by the Board. The first offering period of 2020 started on November 1, 2019 and ended on April 30, 2020, and 97,247 shares were purchased for proceeds of $3.1 million. The second offering period of 2020 started on May 1, 2020 and ended on October 31, 2020. As of September 30, 2020, no shares have been purchased in the second offering period. Stock Options The following table summarizes option activity for the nine months ended September 30, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding Options ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ Shares ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Available for ​ Number of ​ Exercise ​ Contractual ​ Intrinsic (in thousands, except for contractual life and exercise price) ​ Grant ​ Shares ​ Price ​ Life ​ Value ​ ​ ​ ​ ​ ​ ​ ​ ​ (in years) ​ ​ Balance at December 31, 2019 6,416 8,497 ​ $ 10.39 ​ 6.88 ​ $ 197,955 Additional shares authorized 3,120 ​ — ​ ​ ​ ​ ​ ​ ​ ​ Options granted (457) 457 ​ $ 27.61 ​ ​ ​ ​ ​ Options exercised — (1,534) ​ $ 10.28 ​ ​ ​ ​ ​ Options forfeited/cancelled 155 (155) ​ $ 15.40 ​ ​ ​ ​ ​ RSUs granted ​ (5,143) ​ — ​ ​ ​ ​ ​ ​ ​ ​ RSUs forfeited/cancelled ​ 427 ​ — ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, 2020 4,518 7,265 ​ $ 11.39 ​ 6.36 ​ $ 442,004 Exercisable at September 30, 2020 ​ ​ 5,382 ​ $ 9.34 ​ 5.71 ​ $ 338,529 Vested and expected to vest at September 30, 2020 ​ ​ 7,148 ​ $ 11.30 ​ 6.33 ​ $ 435,595 ________________________________ (1) – The RSUs and options are granted under the 2015 Stock Plan. RSUs granted impact the shares available for grant pool at a 2 to 1 ratio. Restricted Stock Units The following table summarizes restricted stock unit (“RSU”) activity for the nine months ended September 30, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ Average ​ ​ ​ ​ Grant Date (in thousands, except for grant date fair value) ​ Shares ​ Fair Value ​ ​ ​ ​ ​ ​ Balance at December 31, 2019 ​ 2,404 ​ $ 19.86 Granted ​ 2,571 ​ $ 29.83 Vested ​ (861) ​ $ 17.48 Cancelled/forfeited ​ (213) ​ $ 24.11 Balance at September 30, 2020 ​ 3,901 ​ $ 25.80 ​ Stock-Based Compensation Expense Stock based compensation is related to stock options and RSUs granted to the Company’s employees and is measured at the grant date based on the fair value of the award. The fair value is recognized as expense over the requisite service period, which is generally the vesting period of the respective awards on a straight-line basis. No compensation cost is recognized when the requisite service has not been met and the awards are therefore forfeited. Employee stock-based compensation expense was calculated based on awards ultimately expected to vest and has been reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods, if actual forfeitures differ from those estimates. Non-employee stock-based compensation expense was not adjusted for estimated forfeitures up until the occurrence of the actual forfeiture of the associated awards. The following tables present the effect of employee and non-employee stock-based compensation expense on selected statements of operations line items for the three months ended September 30, 2020 and 2019. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, ​ ​ 2020 ​ 2019 ​ Employee Non-Employee Total Employee Non-Employee Total ​ ​ (in thousands) Cost of revenues ​ $ 458 ​ $ — ​ $ 458 ​ $ 258 ​ $ 11 ​ $ 269 Research and development ​ 3,081 ​ 17 ​ 3,098 ​ 1,580 ​ — ​ 1,580 Selling, general and administrative ​ 11,404 ​ 72 ​ 11,476 ​ 8,312 ​ 86 ​ 8,398 Total ​ $ 14,943 ​ $ 89 ​ $ 15,032 ​ $ 10,150 ​ $ 97 ​ $ 10,247 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine months ended September 30, ​ ​ 2020 ​ 2019 ​ Employee Non-Employee Total Employee Non-Employee Total ​ (in thousands) ​ Cost of revenues ​ $ 1,213 ​ $ — ​ $ 1,213 ​ $ 641 ​ $ 21 ​ $ 662 ​ Research and development ​ 7,394 ​ 459 ​ 7,853 ​ 3,738 ​ — ​ 3,738 ​ Selling, general and administrative ​ 25,183 ​ 157 ​ 25,340 ​ 15,184 ​ 518 ​ 15,702 ​ Total ​ $ 33,790 ​ $ 616 ​ $ 34,406 ​ $ 19,563 ​ $ 539 ​ $ 20,102 ​ ​ As of September 30, 2020, approximately $89.2 million of unrecognized compensation expense, adjusted for estimated forfeitures, related to unvested option awards and RSUs will be recognized over a weighted-average period of approximately 2.7 years. Valuation of Stock Option Grants to Employees and Non-employees The Company utilizes Black-Scholes option pricing model when estimating the fair value of stock options. For the three and nine months ended September 30, 2020, the following valuation assumptions were applied on both the employee and non-employee options. In the same period of the prior year, the valuation assumptions as follows were only used for stock options granted to employees. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, ​ Nine months ended September 30, ​ 2020 2019 ​ 2020 ​ 2019 ​ Expected term (years) 5.22 ​ — 10.0 ​ 5.23 ​ — 10.00 ​ ​ 5.22 ​ — 10.00 ​ ​ 5.23 ​ — 10.00 ​ Expected volatility 54.18 % ​ 61.96 % 43.07 % — 45.84 % ​ 49.94 % — 61.96 % ​ 42.53 % — 45.84 % Expected dividend rate ​ ​ ​ 0.00 % ​ ​ ​ 0.00 % ​ ​ ​ ​ 0.00 % ​ ​ ​ ​ 0.00 % Risk-free interest rate 0.31 % — 0.65 % 1.60 % — 2.12 % ​ 0.31 % — 1.70 % ​ 1.60 % — 2.60 % ​

Debt

Debt	9 Months Ended
	Sep. 30, 2020
Debt
Debt	10 . Debt Credit Line Agreement In September 2015, the Company entered into a credit line with UBS (the “Credit Line”) providing for a $50.0 million revolving line of credit that can be drawn down in increments at any time. The Credit Line was amended in July 2017 and bears interest at 30-day LIBOR plus 1.10%. The Credit Line is secured by a first priority lien and security interest in the Company’s money market and marketable securities held in its managed investment account with UBS. UBS has the right to demand full or partial payment of the Credit Line Obligations and terminate the Credit Line, in its discretion and without cause, at any time. For the three months ended September 30, 2020 and 2019, the Company recorded interest expense on the Credit Line of $0.2 million and $0.4 million, respectively; and for the nine months ended September 30, 2020 and 2019, interest expense on the Credit Line of $0.7 million and $1.3 million was recorded, respectively. Interest payments on the Credit Line were made within the same periods. As of September 30, 2020, remaining accrued interest was $1.1 million, and the total principal amount outstanding with accrued interest was $49.0 million. 2017 Term Loan . In accordance with ASC Topic 470, the Company accounted for this transaction as debt extinguishment. The difference between the reacquisition price of the debt and the net carrying amount of the debt on the extinguishment date is recorded in loss on debt extinguishment in our condensed consolidated statements of operations and comprehensive loss. The loss on debt extinguishment was computed as follows: ​ ​ ​ ​ ​ ​ September 30, ​ ​ 2020 ​ ​ (in thousands) Debt principal balance ​ $ 75,000 Plus: early payment penalties ​ ​ 3,757 Reacquisition price of debt ​ $ 78,757 ​ ​ ​ ​ Debt principal balance ​ $ 75,000 Less: unamortized debt discount ​ ​ (2,091) Net carrying amount at extinguishment date ​ $ 72,909 ​ ​ ​ ​ Loss on debt extinguishment ​ $ 5,848 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible Notes ​ ​ ​ ​ ​ ● ● ● ● ● ​ ​ ​ trading day immediately preceding the date on which the Company provides notice of redemption. The redemption price will be equal to 100% of the principal amount of the Convertible Notes to be redeemed plus accrued and unpaid interest. The Convertible Notes are accounted for in accordance with ASC 470-20, Debt with Conversion and Other Options, as the Convertible Notes may be settled entirely or partially in cash upon conversion. The Company separately accounted for the liability component and equity component of the Convertible Notes by allocating the debt proceeds between the liability and equity components. The carrying amount of the liability component is calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The Company used a discounted cash flow method and applied the average annual market yield of 7.832% as an input to measure its fair value. The allocation was performed in a manner that reflected the Company’s non-convertible debt borrowing rate for similar debt. The carrying amount of the equity component is determined by deducting the fair value of the liability component from the initial debt proceeds. The fair value of liability component of the Convertible Notes on the date of issuance was $201.9 million, and accordingly, the remaining proceeds of $85.6 million are allocated to the equity component on the date of issuance. The carrying value of the liability component of the Convertible Notes is classified as long-term debt, and the equity component is classified as permanent equity in the Company’s condensed consolidated balance sheet as of September 30, 2020. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ Amount ​ ​ Equity Component ​ ​ Debt Component Debt Discount $ 8,625 ​ $ 2,568 ​ $ 6,057 Debt Issuance Cost ​ 558 ​ ​ 166 ​ ​ 392 Total $ 9,183 ​ $ 2,734 ​ $ 6,449 ​ term. The effective interest rate on the liability component of the Convertible Notes for the period from the date of issuance through May 2027 is ​ ​ ​ ​ ​ ​ September 30, ​ 2020 ​ (in thousands) Liability Component ​ ​ Outstanding Principal $ 287,500 Unamortized debt discount and debt issuance cost ​ (87,541) Net carrying amount $ 199,959 ​ ​ ​ Equity component, net of issuance costs $ 82,873 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended Nine months ended ​ September 30, September 30, ​ 2020 2020 ​ (in thousands) ​ Cash interest expense ​ ​ ​ ​ ​ ​ Contractual interest expense $ 1,617 ​ $ 2,965 ​ Non-cash interest expense ​ ​ ​ ​ ​ ​ Amortization of debt discount and debt issuance cost ​ 2,483 ​ ​ 4,514 ​ Total interest expense $ 4,100 ​ $ 7,479 ​ ​

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Taxes
Income Taxes	11. Income Taxes In response to the COVID-19 pandemic, the Coronavirus Aid, Relief and Economic Security Act (CARES Act) was signed into law in March 2020. The CARES Act includes modifications for net operating loss carryovers and carrybacks, limitations of business interest expense, immediate refund of alternative minimum tax (AMT) credit carryovers as well as a technical correction to the Tax Cuts and Jobs Act of 2017, for qualified improvement property. As of September 30, 2020, the Company expects that these provisions will not have a material impact as the Company has no net operating losses or AMT credits that would fall under these provisions and does not expect interest expense to be deductible due to current and historical losses. During the three and nine months ended September 30, 2020, the Company recorded total income tax expense of approximately $25,000 and $63,000, respectively. During the three and nine months ended September 30, 2019, the Company recorded total income tax expense of approximately $44,000 and $2.0 million, respectively. The income tax expense is primarily attributable to foreign income tax expenses resulting from testing to clinics and licenses cloud-based software and intellectual property, that are based in a foreign country. There was no state income tax expense recorded for the three and nine months ended September 30, 2020. Due to the Company’s history of cumulative operating losses, the Company concluded that, after considering all the available objective evidence, it is not more likely than not that all of the Company’s net deferred tax assets will be realized. Accordingly, all of the Company’s deferred tax assets, which includes net operating loss or NOL carryforwards and tax credits related primarily to research and development, continue to be subjected to a valuation allowance as of September 30, 2020. The Company will continue to maintain a full valuation allowance until there is sufficient evidence to support recoverability of its deferred tax assets. As described in Note 10, Debt ​ The Company had $9.7 million and $8.6 million in unrecognized tax benefits as of September 30, 2020 and December 31, 2019, respectively. The reversal of the uncertain tax benefits would not affect the effective tax rate to the extent that the Company continues to maintain a full valuation allowance against its deferred tax assets. Unrecognized tax benefits may change during the next twelve months for items that arise in the ordinary course of business. Interest and/or penalties related to income tax matters are recognized as a component of income tax expense. As of September 30, 2020, there were no

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2020
Net Loss per Share
Net Loss per Share	12. Net Loss per Share Basic net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, excluding shares subject to repurchase and without consideration of potentially dilutive securities. Diluted net loss per share is computed by giving effect to all potentially dilutive common shares outstanding for the period. For purposes of this computation, outstanding common stock options, and restricted stock units are considered to be common share equivalents. Common share equivalents are excluded from the computation in periods in which they have an anti-dilutive effect, unless the consideration of any one of them gives a dilutive effect. The following table provides the basic and diluted net loss per share computations for the three and nine months ended September 30, 2020 and 2019. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ (in thousands, except per share data) 2020 2019 ​ 2020 2019 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss, basic and diluted $ (58,323) $ (23,137) ​ $ (153,331) $ (89,644) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average number of shares used in computing net loss per share, basic and diluted ​ ​ 80,908 ​ ​ 70,456 ​ ​ 79,430 ​ ​ 67,198 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share, basic and diluted ​ $ (0.72) ​ $ (0.33) ​ $ (1.93) ​ $ (1.33) ​ ​ The following table shows total outstanding potentially dilutive shares excluded from the computation of diluted loss per share as their effect would be anti-dilutive, as of September 30, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2020 2019 ​ (in thousands) Options to purchase common stock ​ 7,265 8,798 Restricted stock units ​ 3,901 ​ 2,269 Employee stock purchase plan ​ 122 ​ 124 Convertible Notes ​ 7,411 ​ — Total ​ 18,699 11,191 ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information. The unaudited interim condensed consolidated financial information includes only adjustments of a normal recurring nature necessary for a fair presentation of the results of operations, financial position, changes in stockholders’ equity, and cash flows. The results of operations for the three and nine months ended September 30, 2020, are not necessarily indicative of the results for the full year or the results for any future periods. The condensed consolidated balance sheet as of December 31, 2019 has been derived from audited financial statements at that date, these financial statements should be read in conjunction with the audited financial statements, and related notes for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 2, 2020.
Liquidity Matters	Liquidity Matters The Company has incurred net losses since its inception and anticipates net losses and negative operating cash flows for the near future. The Company had a net loss of $153.3 million for the nine months ended September 30, 2020 and an accumulated deficit of $852.9 million as of September 30, 2020. As of September 30, 2020, the Company had $209.5 million in cash, cash equivalents, and restricted cash, $600.2 million in marketable securities, $50.1 million of outstanding balance of the Credit Line (as defined in Note 10, Debt Debt The Company continues to develop and commercialize future products and, consequently, it will need to generate additional revenues to achieve future profitability and may need to raise additional equity or debt financing. If the Company raises additional funds by issuing equity securities, its stockholders will experience dilution. Additional debt financing, if available, may involve covenants restricting its operations or its ability to incur additional debt. Any additional debt financing or additional equity that the Company raises may contain terms that are not favorable to it or its stockholders and requires significant debt service payments, which diverts resources from other activities. Additional financing may not be available at all, or in amounts or on terms acceptable to the Company. If the Company is unable to obtain additional financing, it may be required to delay the development and commercialization of its products and significantly scale back its business and operations. In April 2019, the Company completed an underwritten equity offering and sold 6,052,631 shares of its common stock at a price of $19 per share to the public. Before offering expenses of $0.6 million, the Company received proceeds of $108.1 million net of the underwriting discount. In October 2019, the Company completed another underwritten equity offering and sold 6,571,428 shares of its common stock at a price of $35 per share to the public. Before offering expenses of $0.4 million, the Company received proceeds of $216.2 million net of the underwriting discount. In September 2020, the Company completed an additional underwritten equity offering and sold 4,791,665 shares of its common stock at a price of $60.00 per share to the public. Before offering expenses of $0.3 million, the Company received proceeds of $271.0 million net of the underwriting discount. Based on the Company’s current business plan, the Company believes that its existing cash and marketable securities will be sufficient to meet its anticipated cash requirements for at least 12 months after November 5, 2020.
Principles of Consolidation	Principles of Consolidation ​ The accompanying condensed consolidated financial statements include all the accounts of the Company and its subsidiaries. The Company established a subsidiary that operates in the state of Texas to support the Company’s laboratory and operational functions. All intercompany balances and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with generally accepted accounting principles (GAAP) in the United States requires management to make estimates and assumptions about future events that affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Significant items subject to such estimates include the allowance for doubtful accounts calculated based on the average selling price expected to be received from insurance payors, the operating right-of-use assets and the associated lease liabilities, deferred revenues associated with unsatisfied performance obligations, accrued liability for potential refund requests, the valuation of the Convertible Notes, stock-based compensation, the fair value of common stock, income tax uncertainties, and the expected consideration to be received from contracts with customers. These estimates and assumptions are based on management's best estimates and judgment. Management regularly evaluates its estimates and assumptions using historical experience and other factors, including contractual terms and statutory limits; however, actual results could differ from these estimates and could have an adverse effect on the Company's financial statements.
Credit Losses	Credit Losses ​ Trade accounts receivable and other receivables. ​ The following is a roll-forward of the allowances for credit losses related to trade accounts receivable and other receivables for the nine months ended September 30, 2020: ​ ​ ​ ​ ​ ​ September 30, ​ ​ 2020 ​ ​ ​ (in thousands) Beginning balance ​ $ 2,919 Cumulative-effect adjustment upon adoption of ASU 2016-13 ​ ​ 404 Provision for credit losses ​ ​ 1,445 Write-offs ​ ​ (457) Total ​ $ 4,311 ​ ​ ​ ​ ​ Available-for-sale debt securities. ​
Investments	Investments Investments consist primarily of debt securities such as U.S. Treasuries, U.S. agency and municipal bonds. Management determines the appropriate classification of securities at the time of purchase and re-evaluates such determination at each balance sheet date. The Company generally classifies its entire investment portfolio as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company classifies all investments as short-term, irrespective of maturity date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity.
Risk and Uncertainties	Risk and Uncertainties The Company is subject to risks and uncertainties as a result of the COVID-19 pandemic. The extent of the impact of the COVID-19 pandemic on the Company's business is highly uncertain and difficult to predict, and the full extent and duration of the impact of the COVID 19 pandemic on our business, our operations, and the global economy as a whole is not yet known. While the Company’s test volumes as well as overall average selling prices increased in Q3 2020 compared to Q2 2020, the Company cannot predict the potential nature, magnitude and duration of the effects of the COVID-19 pandemic on the macroeconomic environment. Financial instruments that potentially subject the Company to credit risk consist of cash, accounts receivable and investments. The Company limits its exposure to credit loss by placing its cash in financial institutions with high credit ratings. The Company's cash may consist of deposits held with banks that may at times exceed federally insured limits. The Company performs evaluations of the relative credit standing of these financial institutions and limits the amount of credit exposure with any one institution. The Company performs evaluations of financial conditions for insurance carriers, patients, clinics and laboratory partners and generally does not require collateral to support credit sales. For the three and nine months ended September 30, 2020, and 2019, there were no customers exceeding 10% of total revenues on an individual basis. As of September 30, 2020 and December 31, 2019, there were no customers with an outstanding balance exceeding 10% of net accounts receivable.
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Comprehensive loss and its components encompass all changes in equity other than those with stockholders, and include net loss, unrealized gains and losses on available-for-sale marketable securities. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ September 30, ​ September 30, ​ 2020 ​ 2019 ​ 2020 ​ 2019 ​ (in thousands) ​ (in thousands) Beginning balance $ 5,770 ​ $ 795 ​ $ 919 ​ $ (552) Net unrealized gain (loss) on available-for-sale securities, net of tax ​ (600) ​ ​ 63 ​ ​ 4,251 ​ ​ 1,410 Ending balance $ 5,170 ​ $ 858 ​ $ 5,170 ​ $ 858
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) under its accounting standard codifications or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed below, the Company believes that the impact of accounting standards updates recently issued that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. Recently Adopted Accounting Pronouncements Fair Value Measurement In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement Goodwill - Internal-Use Software Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350 ‑ 40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract Credit Losses In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments Collaborative Arrangements Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 Income Taxes New Accounting Pronouncements Not Yet Adopted In March 2020, ASU 2020-04, Reference Rate Reform (Topic 848) In August 2020, ASU 2020-06, Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) In October 2020, ASU 2020-10, Codification Improvements comprehensive income. ASU 2010-10 is effective for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. Early application of the amendments is permitted for public business entities for any annual or interim period for which financial statements have not been issued. The Company is currently evaluating the impact of the adoption of this standard on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2020
Summary of Significant Accounting Policies
Schedule of allowances for credit losses, trade accounts receivable and other receivables	​ ​ ​ ​ ​ ​ September 30, ​ ​ 2020 ​ ​ ​ (in thousands) Beginning balance ​ $ 2,919 Cumulative-effect adjustment upon adoption of ASU 2016-13 ​ ​ 404 Provision for credit losses ​ ​ 1,445 Write-offs ​ ​ (457) Total ​ $ 4,311 ​ ​ ​ ​
Schedule of Accumulated Other Comprehensive Income (Loss)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ September 30, ​ September 30, ​ 2020 ​ 2019 ​ 2020 ​ 2019 ​ (in thousands) ​ (in thousands) Beginning balance $ 5,770 ​ $ 795 ​ $ 919 ​ $ (552) Net unrealized gain (loss) on available-for-sale securities, net of tax ​ (600) ​ ​ 63 ​ ​ 4,251 ​ ​ 1,410 Ending balance $ 5,170 ​ $ 858 ​ $ 5,170 ​ $ 858

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue Recognition
Schedule of disaggregation of revenues by payer types	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ September 30, ​ September 30, ​ ​ 2020 ​ 2019 ​ 2020 ​ 2019 (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Insurance carriers ​ $ 78,004 ​ $ 51,801 ​ $ 216,305 ​ $ 152,779 Laboratory and other partners ​ ​ 13,701 ​ ​ 16,938 ​ ​ 42,426 ​ ​ 42,093 Patients ​ ​ 6,438 ​ ​ 9,170 ​ ​ 19,896 ​ ​ 24,216 Total revenues ​ $ 98,143 ​ $ 77,909 ​ $ 278,627 ​ $ 219,088
Schedule of total revenue by geographic area	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ September 30, ​ September 30, ​ 2020 2019 2020 ​ 2019 (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ United States $ 93,511 ​ $ 64,839 ​ $ 260,999 ​ $ 187,515 ​ Americas, excluding U.S. ​ 1,081 ​ ​ 806 ​ ​ 2,584 ​ ​ 2,391 ​ Europe, Middle East, India, Africa ​ 3,524 ​ ​ 3,497 ​ ​ 10,584 ​ ​ 11,819 ​ Asia Pacific and Other ​ 27 ​ ​ 8,767 ​ ​ 4,460 ​ ​ 17,363 ​ Total revenues $ 98,143 ​ $ 77,909 ​ $ 278,627 ​ $ 219,088 ​
Schedule of beginning and ending balances of accounts receivable and deferred revenues	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Balance at ​ ​ September 30, ​ December 31, (in thousands) ​ 2020 ​ 2019 Assets: ​ ​ ​ ​ ​ ​ Accounts receivable ​ $ 70,674 ​ $ 53,351 Liabilities: ​ ​ ​ ​ ​ ​ Deferred revenue, current portion ​ $ 51,227 ​ $ 56,016 Deferred revenue, long-term portion ​ ​ 23,128 ​ ​ 23,808 Total deferred revenues ​ $ 74,355 ​ $ 79,824
Schedule of changes in the balance of deferred revenues	​ ​ ​ ​ ​ ​ ​ Deferred ​ ​ Revenues ​ ​ (in thousands) Balance at December 31, 2019 ​ $ 79,824 Increase in deferred revenues ​ ​ 1,579 Reclasses from deferred revenues to other short-term liabilities ​ ​ (801) Revenue recognized during the period that was included in ​ ​ (5,290) Revenue recognized from performance obligations satisfied ​ ​ (957) Balance at September 30, 2020 ​ $ 74,355

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Measurements
Summary of financial assets and liabilities measured on recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 ​ December 31, 2019 ​ Level I Level II Level III Total Level I Level II Level III Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Financial Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market deposits ​ $ 178,894 $ — $ — ​ $ 178,894 ​ $ 22,477 $ — $ — ​ $ 22,477 U.S. Treasury securities ​ ​ 530,808 ​ — ​ — ​ ​ 530,808 ​ ​ 293,157 ​ — ​ — ​ ​ 293,157 Municipal securities ​ ​ — ​ 69,397 ​ — ​ ​ 69,397 ​ ​ — ​ 85,908 ​ — ​ ​ 85,908 Total financial assets ​ $ 709,702 $ 69,397 $ — ​ $ 779,099 ​ $ 315,634 $ 85,908 $ — ​ $ 401,542

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2020
Financial Instruments
Schedule of available-for-sale securities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 ​ December 31, 2019 ​ Amortized Gross Gross Estimated Fair Value Amortized Gross Gross Estimated Fair Value ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Money market deposits ​ $ 178,894 ​ $ — ​ $ — ​ $ 178,894 ​ $ 22,477 ​ $ — ​ $ — ​ $ 22,477 U.S. Treasury securities (1) ​ 526,643 ​ ​ 4,173 ​ ​ (8) ​ 530,808 ​ 292,506 ​ 731 ​ (80) ​ 293,157 Municipal securities ​ ​ 68,411 ​ ​ 997 ​ ​ (11) ​ ​ 69,397 ​ ​ 85,638 ​ ​ 277 ​ ​ (7) ​ ​ 85,908 Total ​ $ 773,948 ​ $ 5,170 ​ $ (19) ​ $ 779,099 ​ $ 400,621 ​ $ 1,008 ​ $ (87) ​ $ 401,542 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents (2) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 178,894 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 22,477 Short-term investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 600,205 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 379,065 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 779,099 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 401,542
Summarized portfolio of available-for-sale securities by contractual maturity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2020 ​ ​ Amortized ​ Fair ​ ​ (in thousands) Less than or equal to one year ​ $ 338,583 ​ $ 339,655 Greater than one year but less than five years ​ ​ 256,464 ​ ​ 260,550 Total ​ $ 595,047 ​ $ 600,205

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2020
Balance Sheet Components
Schedule of property and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ Useful Life 2020 2019 ​ ​ (in thousands) Machinery and equipment 3 -5 $ 47,158 ​ $ 36,414 Furniture and fixtures 3 years ​ 1,376 ​ 1,376 Computer equipment 3 years ​ 2,025 ​ 1,828 Capitalized software held for internal use 3 years ​ 7,079 ​ ​ 5,917 Leasehold improvements Lesser of useful life or lease term ​ 14,586 ​ 11,556 Construction-in-process ​ ​ 3,692 ​ 7,716 ​ ​ ​ 75,916 ​ 64,807 Less: Accumulated depreciation and amortization ​ ​ (47,667) ​ (41,524) Total Property and Equipment, net ​ $ 28,249 ​ $ 23,283
Schedule of accrued compensation	​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ 2020 2019 ​ (in thousands) Accrued paid time off $ 2,153 ​ $ 1,850 Accrued commissions 7,376 ​ 5,767 Accrued bonuses 6,964 ​ 5,710 Other accrued compensation 5,957 ​ 2,761 Total accrued compensation $ 22,450 ​ $ 16,088
Schedule of other accrued liabilities	​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ 2020 2019 ​ (in thousands) Reserves for refunds to insurance carriers $ 13,322 ​ $ 9,410 Accrued charges for third-party testing ​ 5,668 ​ ​ 8,408 Testing and laboratory materials from suppliers ​ 8,618 ​ ​ 4,301 Marketing and corporate affairs ​ 3,235 ​ ​ 2,957 Legal, audit and consulting fees 4,666 ​ 2,873 Accrued shipping charges ​ 745 ​ ​ 305 Sales tax payable ​ 1,405 ​ ​ 1,691 Accrued specimen service fees ​ 2,247 ​ ​ 2,269 Clinical trials and studies ​ 1,828 ​ ​ 1,092 Operating lease liabilities, current portion ​ 6,380 ​ ​ 5,739 Fixed asset purchases ​ 1,959 ​ ​ 1,482 Other accrued interest ​ 2,965 ​ ​ — Other accrued expenses 9,855 ​ ​ 8,516 Total other accrued liabilities $ 62,893 ​ $ 49,043
Summary of reserve balance and activities for refunds to insurance carriers	​ ​ ​ ​ ​ ​ ​ ​ September 30, September 30, ​ 2020 2019 ​ (in thousands) Beginning balance $ 9,410 ​ ​ 10,012 Additional reserves 11,912 ​ 7,193 Reserves released and actual refunds (8,000) ​ (8,513) Ending balance $ 13,322 ​ $ 8,692 ​ ​ ​ ​ ​ ​ Released into revenue during the nine months ended $ 2,756 ​ $ 1,895 ​ ​ ​ ​ ​ ​

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Leases
Schedule of lease liabilities	​ ​ ​ ​ ​ September 30, ​ 2020 ​ ​ (in thousands) Operating lease liabilities, current portion included in other accrued liabilities $ 6,380 Operating lease liabilities, long-term portion ​ 21,444 Total operating lease liabilities $ 27,824
Schedule of annual minimum lease payments	​ ​ ​ ​ ​ Operating Leases ​ (in thousands) Year ending December 31: ​ ​ 2020 (remaining 3 months) $ 2,244 2021 ​ 9,067 2022 ​ 9,319 2023 ​ 7,797 2024 ​ 2,400 2025 and thereafter ​ 4,730 ​ ​ 35,557 Less: imputed interest ​ (7,733) Operating lease liabilities $ 27,824

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies
Schedule of material contractual commitments	​ ​ ​ ​ ​ ​ Party Commitments ​ Expiry Date ​ ​ (in thousands) ​ ​ Laboratory instruments supplier $ 4,549 ​ December 2021 Material supplier ​ 13,633 ​ May 2030 Application service providers ​ 10,711 ​ Jan-21 - Dec-24 Gene sequencing reagents and kits provider ​ 473 ​ April 2021 Other material suppliers ​ 10,960 ​ Various Total $ 40,326 ​ ​

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of performance-based awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Period Granted ​ Options Granted ​ RSUs Granted ​ Options Vested ​ RSUs Vested ​ Milestone ​ Valuation Method (in thousands) Q1 2019 ​ 200 ​ 300 ​ 118 ​ 184 ​ (1) ​ Monte-Carlo Simulation Q2 2019 ​ — ​ 188 ​ — ​ — ​ (2) ​ Fair Market Value Q3 2019 ​ — ​ 50 ​ — ​ 25 ​ (1) ​ Monte-Carlo Simulation Q1 2020 ​ 150 ​ 300 ​ 38 ​ 131 ​ (1) ​ Monte-Carlo Simulation Q1 2020 ​ — ​ 436 ​ — ​ 4 ​ (3) ​ Fair Market Value Q1 2020 ​ 129 ​ — ​ — ​ — ​ (3) ​ Black-Scholes-Merton Q2 2020 ​ — ​ 21 ​ — ​ — ​ (3) ​ Fair Market Value Q3 2020 ​ 10 ​ — ​ 7 ​ — ​ (4) ​ Black-Scholes-Merton Q3 2020 ​ — ​ 27 ​ — ​ 3 ​ (3) ​ Fair Market Value ________________________________ (1) The awards will vest based on the achievement of certain values of the Company’s common stock at multiple thresholds within certain periods and are contingent upon the completion of requisite service through the date of such vesting. ​ (2) The vesting of the awards will be triggered after the end of the achievement milestone, as measured by the Company. ​ (3) The awards will vest based on achievement of certain revenue target and are contingent upon the completion of requisite service through the date of such vesting. ​ (4) The awards will vest based on a change of coverage.
Summary of stock option activity	The following table summarizes option activity for the nine months ended September 30, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding Options ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ Shares ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Available for ​ Number of ​ Exercise ​ Contractual ​ Intrinsic (in thousands, except for contractual life and exercise price) ​ Grant ​ Shares ​ Price ​ Life ​ Value ​ ​ ​ ​ ​ ​ ​ ​ ​ (in years) ​ ​ Balance at December 31, 2019 6,416 8,497 ​ $ 10.39 ​ 6.88 ​ $ 197,955 Additional shares authorized 3,120 ​ — ​ ​ ​ ​ ​ ​ ​ ​ Options granted (457) 457 ​ $ 27.61 ​ ​ ​ ​ ​ Options exercised — (1,534) ​ $ 10.28 ​ ​ ​ ​ ​ Options forfeited/cancelled 155 (155) ​ $ 15.40 ​ ​ ​ ​ ​ RSUs granted ​ (5,143) ​ — ​ ​ ​ ​ ​ ​ ​ ​ RSUs forfeited/cancelled ​ 427 ​ — ​ ​ ​ ​ ​ ​ ​ ​ Balance at September 30, 2020 4,518 7,265 ​ $ 11.39 ​ 6.36 ​ $ 442,004 Exercisable at September 30, 2020 ​ ​ 5,382 ​ $ 9.34 ​ 5.71 ​ $ 338,529 Vested and expected to vest at September 30, 2020 ​ ​ 7,148 ​ $ 11.30 ​ 6.33 ​ $ 435,595 ________________________________ (1) – The RSUs and options are granted under the 2015 Stock Plan. RSUs granted impact the shares available for grant pool at a 2 to 1 ratio.
Restricted stock units	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ Average ​ ​ ​ ​ Grant Date (in thousands, except for grant date fair value) ​ Shares ​ Fair Value ​ ​ ​ ​ ​ ​ Balance at December 31, 2019 ​ 2,404 ​ $ 19.86 Granted ​ 2,571 ​ $ 29.83 Vested ​ (861) ​ $ 17.48 Cancelled/forfeited ​ (213) ​ $ 24.11 Balance at September 30, 2020 ​ 3,901 ​ $ 25.80
Summary of stock-based compensation expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, ​ ​ 2020 ​ 2019 ​ Employee Non-Employee Total Employee Non-Employee Total ​ ​ (in thousands) Cost of revenues ​ $ 458 ​ $ — ​ $ 458 ​ $ 258 ​ $ 11 ​ $ 269 Research and development ​ 3,081 ​ 17 ​ 3,098 ​ 1,580 ​ — ​ 1,580 Selling, general and administrative ​ 11,404 ​ 72 ​ 11,476 ​ 8,312 ​ 86 ​ 8,398 Total ​ $ 14,943 ​ $ 89 ​ $ 15,032 ​ $ 10,150 ​ $ 97 ​ $ 10,247 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine months ended September 30, ​ ​ 2020 ​ 2019 ​ Employee Non-Employee Total Employee Non-Employee Total ​ (in thousands) ​ Cost of revenues ​ $ 1,213 ​ $ — ​ $ 1,213 ​ $ 641 ​ $ 21 ​ $ 662 ​ Research and development ​ 7,394 ​ 459 ​ 7,853 ​ 3,738 ​ — ​ 3,738 ​ Selling, general and administrative ​ 25,183 ​ 157 ​ 25,340 ​ 15,184 ​ 518 ​ 15,702 ​ Total ​ $ 33,790 ​ $ 616 ​ $ 34,406 ​ $ 19,563 ​ $ 539 ​ $ 20,102 ​
Performance-based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of assumptions used in valuation of fair value	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2020 Risk-free interest rate ​ 0.61 % — 1.64 % Expected dividend yield ​ ​ ​ ​ 0.00 % Expected volatility ​ 55 % — 65 % Expected term (years) ​ 5.25 ​ — 7.25 ​
Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of assumptions used in valuation of fair value	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, ​ Nine months ended September 30, ​ 2020 2019 ​ 2020 ​ 2019 ​ Expected term (years) 5.22 ​ — 10.0 ​ 5.23 ​ — 10.00 ​ ​ 5.22 ​ — 10.00 ​ ​ 5.23 ​ — 10.00 ​ Expected volatility 54.18 % ​ 61.96 % 43.07 % — 45.84 % ​ 49.94 % — 61.96 % ​ 42.53 % — 45.84 % Expected dividend rate ​ ​ ​ 0.00 % ​ ​ ​ 0.00 % ​ ​ ​ ​ 0.00 % ​ ​ ​ ​ 0.00 % Risk-free interest rate 0.31 % — 0.65 % 1.60 % — 2.12 % ​ 0.31 % — 1.70 % ​ 1.60 % — 2.60 %

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2020
Debt
Schedule of debt extinguishment	​ ​ ​ ​ ​ ​ September 30, ​ ​ 2020 ​ ​ (in thousands) Debt principal balance ​ $ 75,000 Plus: early payment penalties ​ ​ 3,757 Reacquisition price of debt ​ $ 78,757 ​ ​ ​ ​ Debt principal balance ​ $ 75,000 Less: unamortized debt discount ​ ​ (2,091) Net carrying amount at extinguishment date ​ $ 72,909 ​ ​ ​ ​ Loss on debt extinguishment ​ $ 5,848
Summary of Costs of liability and equity components	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) ​ ​ Amount ​ ​ Equity Component ​ ​ Debt Component Debt Discount $ 8,625 ​ $ 2,568 ​ $ 6,057 Debt Issuance Cost ​ 558 ​ ​ 166 ​ ​ 392 Total $ 9,183 ​ $ 2,734 ​ $ 6,449
Schedule of outstanding Convertible Notes	​ ​ ​ ​ ​ September 30, ​ 2020 ​ (in thousands) Liability Component ​ ​ Outstanding Principal $ 287,500 Unamortized debt discount and debt issuance cost ​ (87,541) Net carrying amount $ 199,959 ​ ​ ​ Equity component, net of issuance costs $ 82,873
Summary of interest expense	​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended Nine months ended ​ September 30, September 30, ​ 2020 2020 ​ (in thousands) ​ Cash interest expense ​ ​ ​ ​ ​ ​ Contractual interest expense $ 1,617 ​ $ 2,965 ​ Non-cash interest expense ​ ​ ​ ​ ​ ​ Amortization of debt discount and debt issuance cost ​ 2,483 ​ ​ 4,514 ​ Total interest expense $ 4,100 ​ $ 7,479 ​

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Net Loss per Share
Basic and diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ (in thousands, except per share data) 2020 2019 ​ 2020 2019 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss, basic and diluted $ (58,323) $ (23,137) ​ $ (153,331) $ (89,644) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average number of shares used in computing net loss per share, basic and diluted ​ ​ 80,908 ​ ​ 70,456 ​ ​ 79,430 ​ ​ 67,198 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share, basic and diluted ​ $ (0.72) ​ $ (0.33) ​ $ (1.93) ​ $ (1.33) ​
Total outstanding potentially dilutive shares not included in the calculation of dilutive EPS	​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2020 2019 ​ (in thousands) Options to purchase common stock ​ 7,265 8,798 Restricted stock units ​ 3,901 ​ 2,269 Employee stock purchase plan ​ 122 ​ 124 Convertible Notes ​ 7,411 ​ — Total ​ 18,699 11,191

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Liquidity Matters (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 17, 2019	Apr. 26, 2019	Sep. 30, 2020	Apr. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Oct. 31, 2019	Apr. 23, 2019	Dec. 31, 2018
Policies
Net (loss) income					$ (58,323)	$ (23,137)	$ (153,331)	$ (89,644)
Accumulated deficit			$ 852,906		852,906		852,906		$ 699,171
Cash, cash equivalents and restricted cash			209,529		209,529	$ 51,664	209,529	$ 51,664	61,981			$ 51,004
Marketable securities			600,205		600,205		600,205		379,065
Short-term Credit Line, outstanding balance			$ 50,052		$ 50,052		$ 50,052		$ 50,123
Common stock, shares issued			85,281,000		85,281,000		85,281,000		78,005,000
Payment of offering expenses	$ 400	$ 600	$ 300
Proceeds from issuance of common stock	$ 216,200	$ 108,100	271,000
Net proceeds							$ 278,316
Debt principal balance			75,000		$ 75,000		75,000
Loss on Debt Extinguishment							5,848
Convertible Notes
Policies
Outstanding principal balance			287,500	$ 287,500	287,500		$ 287,500
Per annum interest rate (as a percent)				2.25%			2.25%
Net proceeds				$ 278,300
Debt principal balance			$ 287,500		$ 287,500		$ 287,500
Equity offering
Policies
Common stock, shares issued			4,791,665		4,791,665		4,791,665			6,571,428	6,052,631
Stock issued (in dollars per share)	$ 35		$ 60		$ 60		$ 60				$ 19

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Credit Losses (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Summary of Significant Accounting Policies
Beginning balance	$ 2,919
Cumulative-effect adjustment upon adoption of ASU 2016-13	404
Provision for credit losses	1,445
Write offs	(457)
Total	$ 4,311

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Concentration (Details) - customer	3 Months Ended		9 Months Ended		12 Months Ended	21 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Sep. 30, 2020
Sales | Customer
Risk and Uncertainties
Number of customers exceeding 10% of benchmark	0	0	0	0
Concentration risk (as a percent)						10.00%
Accounts receivable | Credit
Risk and Uncertainties
Number of customers exceeding 10% of benchmark			0		0
Concentration risk (as a percent)						10.00%

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - AOCIL (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 5,770	$ 795	$ 919	$ (552)
Ending balance	5,170	858	5,170	858
Net unrealized gain (loss) on available-for-sale securities, net of tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on available-for-sale securities, net of tax	$ (600)	$ 63	$ 4,251	$ 1,410

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Accounting Pronouncements (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment	$ 404
ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment		$ 400

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2019	Feb. 28, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Revenue recognized					$ 2,756	$ 1,895
Deferred revenue, Long-term			$ 23,128		23,128		$ 23,808
Other assets			12,156		12,156		12,476
Deferred revenue			74,355		74,355		79,824
Deferred revenue, current portion			51,227		51,227		56,016
Total revenues			98,143	$ 77,909	278,627	219,088
Deferred revenue, long-term portion			23,128		23,128		23,808
Revenue recognized during the period that was included in deferred revenues at the beginning of the period					5,290
Product
Revenue recognized			1,100	600	2,700	1,900
Cost of revenues			46,873	40,138	131,124	123,125
Total revenues			93,286	66,936	$ 260,746	195,399
Product | Minimum
Billing collection period (in months)					9 months
Product | Maximum
Billing collection period (in months)					12 months
Licensing and other
Cost of revenues			4,948	3,742	$ 12,614	7,883
Total revenues			4,857	10,973	17,881	23,689
Genetic testing services
Revenue recognized during the period that was included in deferred revenues at the beginning of the period					$ 400
Qiagen
Proceeds from license agreement								$ 5,000
Agreement term					10 years
Revenue, remaining performance obligation								40,000
Qiagen | Volume, regulatory and commercial milestones
Revenue, remaining performance obligation								$ 10,000
Qiagen | Prepaid royalty
Revenue recognized			0
Laboratory distribution partners | Product | Minimum
Billing collection period (in months)					2 months
Laboratory distribution partners | Product | Maximum
Billing collection period (in months)					3 months
BGI Genomics
Proceeds from license agreement		$ 50,000		35,600
Receivable				2,500		2,500
Agreement term		10 years
Deferred revenue, current portion			4,700		$ 4,700
BGI Genomics | Sequencing services
Other assets				6,000		6,000
BGI Genomics | Sequencing products
Other assets				4,000		4,000
BGI Genomics | Sequencing products and services
Other assets			10,000	$ 10,000	10,000	$ 10,000
Foundation Medicine ("FMI")
Proceeds from license agreement					0		16,300
Agreement term	5 years
Automatic renewals, successive period thereafter	1 year
Deferred revenue, current portion			$ 7,000		7,000
Foundation Medicine ("FMI") | Upfront licensing fees and prepaid revenues
Initial transaction price	$ 13,300
Foundation Medicine ("FMI") | Developmental, regulatory, and commercial milestones
Initial transaction price	$ 32,000
Foundation Medicine ("FMI") | Developmental performance milestones
Proceeds from license agreement							3,000
Foundation Medicine ("FMI") | Licensing fees and prepaid revenue
Proceeds from license agreement							$ 13,300
BGI and FMI | Genetic testing services
Revenue recognized during the period that was included in deferred revenues at the beginning of the period					$ 4,900

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 98,143	$ 77,909	$ 278,627	$ 219,088
United States
Disaggregation of Revenue [Line Items]
Total revenues	93,511	64,839	260,999	187,515
Americas, excluding U.S.
Disaggregation of Revenue [Line Items]
Total revenues	1,081	806	2,584	2,391
Europe, Middle East, India, Africa
Disaggregation of Revenue [Line Items]
Total revenues	3,524	3,497	10,584	11,819
Asia Pacific and Other
Disaggregation of Revenue [Line Items]
Total revenues	27	8,767	4,460	17,363
Insurance carriers
Disaggregation of Revenue [Line Items]
Total revenues	78,004	51,801	216,305	152,779
Laboratory and other partners
Disaggregation of Revenue [Line Items]
Total revenues	13,701	16,938	42,426	42,093
Patients
Disaggregation of Revenue [Line Items]
Total revenues	6,438	9,170	19,896	24,216
Product
Disaggregation of Revenue [Line Items]
Total revenues	93,286	66,936	260,746	195,399
Licensing and other
Disaggregation of Revenue [Line Items]
Total revenues	$ 4,857	$ 10,973	$ 17,881	$ 23,689

Revenue Recognition - Accounts

Revenue Recognition - Accounts Receivable and Deferred Revenue (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
Accounts receivable	$ 70,674	$ 53,351
Liabilities:
Deferred revenue, current portion	51,227	56,016
Deferred revenue, long-term portion	23,128	23,808
Total deferred revenues	74,355	79,824
Current accounts receivable	70,674	53,351
Other noncurrent assets	$ 12,156	$ 12,476

Revenue Recognition - Changes i

Revenue Recognition - Changes in Balance of Deferred Revenues (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Revenue Recognition
Balance	$ 79,824
Increase in deferred revenues	1,579
Reclasses from deferred revenues to other short-term liabilities	(801)
Revenue recognized during the period that was included in deferred revenues at the beginning of the period	(5,290)
Revenue recognized from performance obligations satisfied within the same period	(957)
Balance	$ 74,355

Revenue Recognition - Deferred

Revenue Recognition - Deferred Revenues (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Revenue recognized during the period that was included in deferred revenues at the beginning of the period	$ 5,290
Deferred revenue, current portion	51,227	$ 56,016
Deferred revenue, Long-term	23,128	23,808
Total deferred revenues	74,355	$ 79,824
BGI Genomics
Deferred revenue, current portion	4,700
Foundation Medicine ("FMI")
Deferred revenue, current portion	7,000
BGI Genomics and Foundation Medicine ("FMI")
Revenue recognized during the period that was included in deferred revenues at the beginning of the period	$ 1,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Available-for-sale securities
Fair Value Measurements
Unrealized losses	$ 122,900
Recurring
Financial Assets:
Total financial assets	779,099	$ 401,542
Recurring | Money market deposits
Financial Assets:
Total financial assets	178,894	22,477
Recurring | U.S. Treasury securities
Financial Assets:
Total financial assets	530,808	293,157
Recurring | Municipal securities
Financial Assets:
Total financial assets	69,397	85,908
Recurring | Level 1
Financial Assets:
Total financial assets	709,702	315,634
Recurring | Level 1 | Money market deposits
Financial Assets:
Total financial assets	178,894	22,477
Recurring | Level 1 | U.S. Treasury securities
Financial Assets:
Total financial assets	530,808	293,157
Recurring | Level 2
Financial Assets:
Total financial assets	69,397	85,908
Recurring | Level 2 | Municipal securities
Financial Assets:
Total financial assets	$ 69,397	85,908
Contingent consideration | Evercord
Liabilities:
Total consideration		$ 4,700

Financial Instruments (Details)

Financial Instruments (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)position	Dec. 31, 2019USD ($)
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Estimated Fair Value	$ 600,205	$ 379,065
Other than temporary impairment	0
Amount of investments sold	$ 11,500
Number of investments, unrealized loss position | position	8
Amortized Cost
Less than or equal to one year	$ 338,583
Greater than one year but less than five years	256,464
Total	595,047
Fair Value
Less than one year	339,655
Greater than or equal to one year but less than five years	260,550
Total	600,205
Available-for-sale securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	773,948	400,621
Unrealized Gain	5,170	1,008
Unrealized Loss	(19)	(87)
Estimated Fair Value	779,099	401,542
Unrealized loss position	122,900
Money market deposits
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	178,894	22,477
Estimated Fair Value	178,894	22,477
U.S. Treasury securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	526,643	292,506
Unrealized Gain	4,173	731
Unrealized Loss	(8)	(80)
Estimated Fair Value	530,808	293,157
Municipal securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Amortized Cost	68,411	85,638
Unrealized Gain	997	277
Unrealized Loss	(11)	(7)
Estimated Fair Value	69,397	85,908
Cash equivalents | Available-for-sale securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Estimated Fair Value	178,894	22,477
Short-term investments | Available-for-sale securities
Debt Securities, Available-for-sale, Fair Value to Amortized Cost [Abstract]
Estimated Fair Value	$ 600,205	$ 379,065

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019
Property and Equipment, net
Property and equipment, gross	$ 75,916		$ 75,916	$ 64,807
Less: Accumulated depreciation and amortization	(47,667)		(47,667)	(41,524)
Total Property and Equipment, net	28,249		28,249	23,283
Depreciation expense			6,200
Impairment	0	$ 1,310
Machinery and equipment
Property and Equipment, net
Property and equipment, gross	47,158		47,158	36,414
Furniture and fixtures
Property and Equipment, net
Property and equipment, gross	1,376		$ 1,376	1,376
Useful Life			3 years
Computer equipment
Property and Equipment, net
Property and equipment, gross	2,025		$ 2,025	1,828
Useful Life			3 years
Capitalized software held for internal use
Property and Equipment, net
Property and equipment, gross	7,079		$ 7,079	5,917
Useful Life			3 years
Leasehold improvements
Property and Equipment, net
Property and equipment, gross	14,586		$ 14,586	11,556
Construction-in-process
Property and Equipment, net
Property and equipment, gross	$ 3,692		$ 3,692	$ 7,716
Minimum | Machinery and equipment
Property and Equipment, net
Useful Life			3 years
Maximum | Machinery and equipment
Property and Equipment, net
Useful Life			5 years

Balance Sheet Components - Othe

Balance Sheet Components - Other Assets (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Apr. 30, 2020	Dec. 31, 2019	Apr. 30, 2019	Aug. 31, 2017	Aug. 08, 2017
Balance Sheet Components [Line Items]
Common stock, shares issued		85,281,000		78,005,000
Amortization of debt discount and issuance cost	$ 336	$ 149
Noncurrent assets		12,156		$ 12,476
Convertible Notes
Balance Sheet Components [Line Items]
Debt discount			$ 8,600
Evercord
Balance Sheet Components [Line Items]
Net collections		2,000
Credit loss expense		1,200
Evercord | Contingent consideration
Balance Sheet Components [Line Items]
Total consideration				$ 4,700
Noncurrent assets
Balance Sheet Components [Line Items]
Debt discount		0
Long-term Debt
Balance Sheet Components [Line Items]
Debt discount		900
2017 Term Loan
Balance Sheet Components [Line Items]
Common stock, shares issued					25,000	300,000
Remaining borrowing capacity		50,000				$ 50,000	$ 25,000
2017 Term Loan | Noncurrent assets
Balance Sheet Components [Line Items]
Debt instrument, fee amount						$ 1,200
Evercord | Contingent consideration
Balance Sheet Components [Line Items]
Accounts receivable		1,500
BGI Genomics | Sequencing products and services
Balance Sheet Components [Line Items]
Noncurrent assets	$ 10,000	$ 10,000

Balance Sheet Components - Impa

Balance Sheet Components - Impairment for Receivables (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Balance Sheet Components
Impairment	$ 0	$ 1,310

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Compensation (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Balance Sheet Components
Accrued paid time off	$ 2,153	$ 1,850
Accrued commissions	7,376	5,767
Accrued bonuses	6,964	5,710
Other accrued compensation	5,957	2,761
Total accrued compensation	$ 22,450	$ 16,088

Balance Sheet Components - Ot_2

Balance Sheet Components - Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Balance Sheet Components
Reserves for refunds to insurance carriers	$ 13,322	$ 9,410	$ 8,692	$ 10,012
Accrued charges for third-party testing	5,668	8,408
Testing and laboratory materials from suppliers	8,618	4,301
Marketing and corporate affairs	3,235	2,957
Legal, audit and consulting fees	4,666	2,873
Accrued shipping charges	745	305
Sales tax payable	1,405	1,691
Accrued specimen service fees	2,247	2,269
Clinical trials and studies	1,828	1,092
Operating lease liabilities, current portion	6,380	5,739
Fixed asset purchases	1,959	1,482
Other accrued interest	2,965
Other accrued expenses	9,855	8,516
Total other accrued liabilities	$ 62,893	$ 49,043

Balance Sheet Components - Rese

Balance Sheet Components - Reserve Balance and Activities for Refunds (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Balance Sheet Components
Beginning balance	$ 9,410	$ 10,012
Additional reserves	11,912	7,193
Reserves released and actual refunds	(8,000)	(8,513)
Ending balance	13,322	8,692
Released into revenue during the nine months ended	$ 2,756	$ 1,895

Leases (Details)

Leases (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)ft²	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)ft²location	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Jun. 30, 2019USD ($)ft²
Lessee, Lease, Description [Line Items]
Operating lease liabilities, current portion included in other accrued liabilities | $	$ 6,380		$ 6,380		$ 5,739
Operating lease liabilities, long-term portion | $	21,444		21,444		$ 26,297
Operating lease liabilities | $	$ 27,824		$ 27,824
Weighted average remaining lease term	2 years 6 months 25 days		2 years 6 months 25 days
Weighted average discount rate (as a percent)	10.77%		10.77%
Lease expense | $	$ 1,900	$ 2,000	$ 5,800	$ 5,800
Operating lease payments | $	$ 2,200			$ 6,600
Corporate Headquarters Lease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	113,000		113,000
Number of office space locations | location			2
Term of lease	84 months		84 months
Renewal term of lease	5 years		5 years
"First Space" Sublease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	88,000		88,000
"Second Space" Sublease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	25,000		25,000
Corporate Headquarters Sublease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²						25,879
Term of lease						48 months
Sublease receivable | $						$ 1,900
Tukwila, WA lease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	10,000		10,000
Term of lease	62 months		62 months
Renewal term of lease	5 years		5 years
Austin TX, Long-term Lease
Lessee, Lease, Description [Line Items]
Office space (area) | ft²	94,000		94,000
Term of lease	132 months		132 months

Leases - Payments (Details)

Leases - Payments (Details) $ in Thousands	Sep. 30, 2020USD ($)
Leases
2020 (remaining 3 months)	$ 2,244
2021	9,067
2022	9,319
2023	7,797
2024	2,400
2025 and thereafter	4,730
Total	35,557
Less: imputed interest	(7,733)
Operating lease liabilities	$ 27,824

Commitments and Contingencies_2

Commitments and Contingencies (Details) $ in Thousands	Sep. 30, 2020USD ($)
Other commitments
Total commitments	$ 40,326
Laboratory instruments supplier
Other commitments
Total commitments	4,549
Material supplier
Other commitments
Total commitments	13,633
Application service provider
Other commitments
Total commitments	10,711
Gene sequencing reagents and kits
Other commitments
Total commitments	473
Other material supplier
Other commitments
Total commitments	10,960
Securities related claims
Other commitments
Estimate of possible loss	1,500
Commercial general liability claims
Other commitments
Estimate of possible loss	$ 300

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		5 Months Ended	6 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Apr. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Jun. 30, 2015
2015 Plan
Stock Based Compensation
Shares reserved for issuance								3,451,495
Additional shares reserved for issuance								9,890,310
Performance-based awards
Stock Based Compensation
Stock-based compensation expense	$ 6,600	$ 400			$ 11,800	$ 600
Employee and non-employee stock options
Stock Based Compensation
Stock-based compensation expense	$ 15,032	$ 10,247			$ 34,406	$ 20,102
Shares granted					5,143,000
Shares available for issuance	4,518,000		4,518,000		4,518,000		6,416,000
Restricted stock units
Stock Based Compensation
Number of shares vested					861,000
Shares granted					2,571,000
2015 Employee Stock Purchase Plan
Stock Based Compensation
Shares reserved for issuance	893,548		893,548		893,548
Shares granted			0	97,247
Proceeds from shares purchased				$ 3,100
Shares reserved for issuance as a proportion common stock outstanding (as a percent)					1.00%
2015 Employee Stock Purchase Plan | Minimum
Stock Based Compensation
Shares reserved for issuance	880,000		880,000		880,000

Stock-Based Compensation - Perf

Stock-Based Compensation - Performance-based Awards (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Market Value
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Valuation Method	Fair Market Value	Fair Market Value	Fair Market Value		Fair Market Value
Black-Scholes Merton
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Valuation Method	Black-Scholes-Merton		Black-Scholes-Merton
Monte-Carlo
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Valuation Method			Monte-Carlo Simulation	Monte-Carlo Simulation		Monte-Carlo Simulation
Performance-based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 6,600			$ 400			$ 11,800	$ 600
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs Granted (in shares)							2,571
Vested (in shares)							861
Restricted stock units | Fair Market Value
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs Granted (in shares)	27	21	436		188
Vested (in shares)	3		4
Restricted stock units | Monte-Carlo
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs Granted (in shares)			300	50		300
Vested (in shares)			131	25		184
Employee and non-employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Granted (in shares)							457
RSUs Granted (in shares)							5,143
Stock-based compensation expense	$ 15,032			$ 10,247			$ 34,406	$ 20,102
Employee and non-employee stock options | Black-Scholes Merton
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Granted (in shares)	10		129
Options Vested (in shares)	7
Number of options vested	7
Employee and non-employee stock options | Monte-Carlo
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Granted (in shares)			150			200
Options Vested (in shares)			38			118
Number of options vested			38			118

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares
Employee and non-employee stock options
Stock Based Compensation
Shares available for grant, beginning balance	6,416
Additional shares authorized	3,120
Options granted (in shares)	(457)
Options forfeited (in shares)	155
RSUs granted (in shares)	(5,143)
RSUs forfeited/cancelled (in shares)	427
Shares available for grant, end balance	4,518	6,416
Number of shares
Outstanding, beginning balance (in shares)	8,497
Options granted (in shares)	457
Options exercised (in shares)	(1,534)
Options forfeited (in shares)	(155)
Outstanding, end balance (in shares)	7,265	8,497
Exercisable (in shares)	5,382
Vested and expected to vest (in shares)	7,148
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 10.39
Granted (in dollars per share) | $ / shares	27.61
Exercised (in dollars per share) | $ / shares	10.28
Forfeited (in dollars per share) | $ / shares	15.40
Outstanding, end balance (in dollars per share) | $ / shares	11.39	$ 10.39
Exercisable (in dollars per share) | $ / shares	9.34
Vested and expected to vest (in dollars per share) | $ / shares	$ 11.30
Additional disclosures
Weighted average contractual term, options outstanding	6 years 4 months 9 days	6 years 10 months 17 days
Exercisable (in years)	5 years 8 months 15 days
Vested and expected to vest (in years)	6 years 3 months 29 days
Aggregate intrinsic value, options outstanding | $	$ 442,004	$ 197,955
Aggregate intrinsic value, options exercisable | $	338,529
Aggregate intrinsic value, vested and expected to vest | $	$ 435,595
Restricted stock units
Stock Based Compensation
RSUs granted (in shares)	(2,571)
RSUs forfeited/cancelled (in shares)	213
Additional disclosures
RSUs granted, impact on shares available for grant pool, ratio	2

Stock-Based Compensation - Assu

Stock-Based Compensation - Assumptions (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Performance-based awards
Valuation of Stock Option Grants to Employees
Expected volatility, minimum			55.00%
Expected volatility, maximum			65.00%
Risk free interest rate, minimum			0.61%
Risk free interest rate, maximum			1.64%
Performance-based awards | Minimum
Valuation of Stock Option Grants to Employees
Expected term (years)			5 years 3 months
Performance-based awards | Maximum
Valuation of Stock Option Grants to Employees
Expected term (years)			7 years 3 months
Expected dividend yield			0.00%
Employee and non-employee stock options
Stock Based Compensation
Options granted (in shares)			457,000
Employee stock options
Valuation of Stock Option Grants to Employees
Expected volatility	61.96%
Expected volatility, minimum	54.18%	43.07%	49.94%	42.53%
Expected volatility, maximum		45.84%	61.96%	45.84%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk free interest rate	0.65%
Risk free interest rate, minimum	0.31%	1.60%	0.31%	1.60%
Risk free interest rate, maximum		2.12%	1.70%	2.60%
Employee stock options | Minimum
Valuation of Stock Option Grants to Employees
Expected term (years)	5 years 2 months 19 days	5 years 2 months 23 days	5 years 2 months 19 days	5 years 2 months 23 days
Employee stock options | Maximum
Valuation of Stock Option Grants to Employees
Expected term (years)	10 years	10 years	10 years	10 years
Non-employee stock options
Stock Based Compensation
Options granted (in shares)			51,737
Options unvested (in shares)	7,814		7,814

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units (Details) - Restricted stock units shares in Thousands	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Shares
Balance (in shares) | shares	2,404
Granted (in shares) | shares	2,571
Vested (in shares) | shares	(861)
Canceled/Forfeited (in shares) | shares	(213)
Balance (in shares) | shares	3,901
Weighted Average Grant Date Fair Value
Balance (in dollars per share) | $ / shares	$ 19.86
Granted (in dollars per share) | $ / shares	29.83
Vested (in dollars per share) | $ / shares	17.48
Canceled/Forfeited (in dollars per share) | $ / shares	24.11
Balance (in dollars per share) | $ / shares	$ 25.80

Stock-Based Compensation - Comp

Stock-Based Compensation - Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Employee and non-employee stock options
Stock based compensation expense
Options granted (in shares)			457,000
Stock-based compensation expense	$ 15,032	$ 10,247	$ 34,406	$ 20,102
Unrecognized compensation expense	89,200		$ 89,200
Unrecognized compensation expense, weighted average period of recognition			2 years 8 months 12 days
Employee and non-employee stock options | Cost of revenues
Stock based compensation expense
Stock-based compensation expense	458	269	$ 1,213	662
Employee and non-employee stock options | Research and development
Stock based compensation expense
Stock-based compensation expense	3,098	1,580	7,853	3,738
Employee and non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock-based compensation expense	11,476	8,398	25,340	15,702
Employee stock options
Stock based compensation expense
Stock-based compensation expense	14,943	10,150	33,790	19,563
Employee stock options | Cost of revenues
Stock based compensation expense
Stock-based compensation expense	458	258	1,213	641
Employee stock options | Research and development
Stock based compensation expense
Stock-based compensation expense	3,081	1,580	7,394	3,738
Employee stock options | Selling, general and administrative
Stock based compensation expense
Stock-based compensation expense	$ 11,404	8,312	$ 25,183	15,184
Non-employee stock options
Stock based compensation expense
Options granted (in shares)			51,737
Options unvested (in shares)	7,814		7,814
Stock-based compensation expense	$ 89	97	$ 616	539
Non-employee stock options | Cost of revenues
Stock based compensation expense
Stock-based compensation expense		11		21
Non-employee stock options | Research and development
Stock based compensation expense
Stock-based compensation expense	17		459
Non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock-based compensation expense	$ 72	$ 86	$ 157	$ 518

Debt (Details)

Debt (Details)	Sep. 30, 2020USD ($)$ / sharesshares	Apr. 30, 2020USD ($)D	Sep. 30, 2020USD ($)$ / sharesshares	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)$ / sharesshares	Sep. 30, 2019USD ($)	Dec. 31, 2019$ / sharesshares	Apr. 30, 2019shares	Aug. 31, 2017USD ($)shares	Aug. 08, 2017USD ($)	Sep. 30, 2015USD ($)
Debt Instrument [Line Items]
Proceeds from Convertible Note, net of issuance costs					$ 278,316,000
Unamortized debt discount	$ 2,091,000		$ 2,091,000		$ 2,091,000
Common Stock, Par or Stated Value Per Share | $ / shares	$ 0.0001		$ 0.0001		$ 0.0001		$ 0.0001
Issuance of common stock to Orbimed (in shares) | shares					25,000
Issuance of common stock to Orbimed						$ 506,000
Common stock, shares issued | shares	85,281,000		85,281,000		85,281,000		78,005,000
Debt, repayment amount					$ 79,200,000
Payment of accrued interest					400,000
Accrued Interest	$ 2,965,000		$ 2,965,000		2,965,000
Amortization of debt discount and issuance cost				$ 336,000	149,000
Interest expense			4,270,000	2,672,000	10,772,000	8,117,000
Convertible Notes
Debt Instrument [Line Items]
Aggregate principal amount	287,500,000	$ 287,500,000	287,500,000		$ 287,500,000
Proceeds from Convertible Note, net of issuance costs		$ 278,300,000
Per annum interest rate (as a percent)		2.25%			2.25%
Interest expense			4,100,000		$ 7,479,000
Unamortized debt discount	$ 8,625,000		$ 8,625,000		$ 8,625,000
Common Stock, Par or Stated Value Per Share | $ / shares	$ 0.001		$ 0.001		$ 0.001
Debt instrument, term		7 years
Effective interest rate (as a percent)		8.27%
Principal amount per convertible note		$ 1,000
Number of threshold consecutive trading days | D		30
Threshold business days | D		5
Convertible, If-converted value in excess of principal	$ 173,000,000
Conversion price (in dollars per share) | $ / shares	$ 38.79		$ 38.79		$ 38.79
Initial conversion rate	25.7785
Convertible to shares of common stock	7,411,704
Percentage of principal amount converted	100.00%
Fair value of liability		$ 201,900,000
Carrying value	$ 199,959,000		$ 199,959,000		$ 199,959,000
Equity component	82,873,000	85,600,000	82,873,000		82,873,000
Debt Instrument, debt discount, Equity Component	81,400,000		81,400,000		81,400,000
Debt Instrument, debt discount, Liability Component	5,700,000		5,700,000		5,700,000
Debt issuance costs	558,000	$ 600,000	558,000		558,000
5 consecutive trading day period | Convertible Notes
Debt Instrument [Line Items]
Threshold trading days | D		5
Percentage of conversion price		98.00%
20 trading days period | Convertible Notes
Debt Instrument [Line Items]
Threshold trading days | D		20
Percentage of conversion price		130.00%
Redeemable for cash on or after May 2024
Debt Instrument [Line Items]
Number of threshold consecutive trading days | D		20
Threshold trading days | D		30
Percentage of conversion price		130.00%
Percentage of principal amount converted		100.00%
Debt Component | Convertible Notes
Debt Instrument [Line Items]
Unamortized debt discount	6,057,000		6,057,000		6,057,000
Debt issuance costs	392,000		392,000		392,000
Measurement input, risk free interest rate | Convertible Notes
Debt Instrument [Line Items]
Debt Instrument, Measurement Input		7.832
Level 2 | Convertible Notes
Debt Instrument [Line Items]
Fair value of liability	201,900,000		201,900,000		201,900,000
Line Of Credit-UBS
Debt Instrument [Line Items]
Maximum borrowing capacity											$ 50,000,000
Outstanding balance	49,000,000		49,000,000		49,000,000
Accrued interest	1,100,000		1,100,000		1,100,000
Interest expense			200,000	$ 400,000	$ 700,000	1,300,000
Line Of Credit-UBS | LIBOR
Debt Instrument [Line Items]
Spread on interest rate (as a percent)					1.10%
2017 Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity									$ 100,000,000
Remaining borrowing capacity	50,000,000		50,000,000		$ 50,000,000				$ 50,000,000	$ 25,000,000
Outstanding balance										$ 75,000,000
Common stock, shares issued | shares								25,000	300,000
Debt, repayment amount		$ 79,200,000
Interest expense					2,500,000	$ 6,500,000
2017 Term Loan | Minimum
Debt Instrument [Line Items]
Remaining borrowing capacity	$ 25,000,000		$ 25,000,000		$ 25,000,000
2017 Term Loan | LIBOR
Debt Instrument [Line Items]
Spread on interest rate (as a percent)					8.75%
Base interest rate (as a percent)					1.00%
2017 Term Loan | LIBOR | Minimum borrowing capacity drawn
Debt Instrument [Line Items]
Spread on interest rate (as a percent)					8.25%
Base interest rate (as a percent)					1.00%
2017 Term Loan | Noncurrent assets
Debt Instrument [Line Items]
Debt instrument, fee amount									$ 1,200,000

Debt - Carrying Amount (Details

Debt - Carrying Amount (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Debt
Debt principal balance	$ 75,000
Plus: early payment penalties	3,757
Reacquisition price of debt	78,757
Less: unamortized debt discount	(2,091)
Net carrying amount at extinguishment date	72,909
Loss on debt extinguishment	$ 5,848

Debt - Discount and Issuance Co

Debt - Discount and Issuance Costs (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Apr. 30, 2020
Debt Discount	$ 2,091
Convertible Notes
Debt Discount	8,625
Debt Issuance Cost	558	$ 600
Total	9,183	$ 9,200
Convertible Notes | Equity Component
Debt Discount	2,568
Debt Issuance Cost	166
Total	2,734
Convertible Notes | Debt Component
Debt Discount	6,057
Debt Issuance Cost	392
Total	$ 6,449

Debt - Outstanding Convertible

Debt - Outstanding Convertible Notes Balances (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Apr. 30, 2020
Debt principal balance	$ 75,000
Convertible Notes
Debt principal balance	287,500
Unamortized debt discount and debt issuance cost	(87,541)
Net carrying amount	199,959
Equity component, net of issuance costs	$ 82,873	$ 85,600

Debt - Interest Expense Recogni

Debt - Interest Expense Recognized Related To Convertible Notes (Details) - Convertible Notes - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Cash interest expense
Contractual interest expense	$ 1,617	$ 2,965
Non-cash interest expense
Amortization of debt discount and debt issuance cost	2,483	4,514
Total interest expense	$ 4,100	$ 7,479

Income taxes (Details)

Income taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Income Taxes
Income tax expense	$ 25,000	$ 44,000	$ 63,000	$ 2,013,000
State income tax expense	0		0
Unrecognized tax benefits	9,700,000		9,700,000		$ 8,600,000
Interest and penalties accrued	$ 0		$ 0

Net Loss per Share - Loss per S

Net Loss per Share - Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss, basic and diluted	$ (58,323)	$ (23,137)	$ (153,331)	$ (89,644)
Denominator:
Weighted-average number of shares used in computing net loss per share, basic and diluted	80,908	70,456	79,430	67,198
Net loss per share, basic and diluted (in dollars per share)	$ (0.72)	$ (0.33)	$ (1.93)	$ (1.33)

Net Loss per Share - Potentiall

Net Loss per Share - Potentially Dilutive Shares (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations	18,699	11,191
Employee and non-employee stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations	7,265	8,798
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations	3,901	2,269
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations	122	124
Convertible Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations	7,411