Natera (NTRA) 10-K 16 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2016	Feb. 28, 2017	Jun. 30, 2016
Document and Entity Information
Entity Registrant Name	Natera, Inc.
Entity Central Index Key	1,604,821
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 0.5
Entity Common Stock, Shares Outstanding		52,772,984
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 15,256	$ 28,947
Restricted cash, current portion	1,092	901
Short-term investments	130,860	201,586
Accounts receivable, net of allowance of $1,890 in 2016 and $971 in 2015	13,396	5,862
Inventory	6,414	8,093
Prepaid expenses and other current assets	7,097	5,337
Total current assets	174,115	250,726
Property and equipment, net	32,289	12,710
Restricted cash, long term portion	342	683
Other assets	3,934	1,121
Total assets	210,680	265,240
Current liabilities:
Accounts payable	11,479	7,332
Accrued compensation	11,067	8,552
Other accrued liabilities	19,879	18,708
Deferred revenue	574	144
Short-term debt financing	49,624	42,090
Warrants	3,792	3,649
Total current liabilities	96,415	80,475
Deferred rent, net of current portion	7,789
Total liabilities	104,204	80,475
Commitments and contingencies (Note 6)
Stockholders' equity:
Preferred stock, $0.0001 par value: 50,000 shares authorized; no shares issued and outstanding at December 31, 2016 and 2015, respectively
Common stock, $0.0001 par value: 750,000 shares authorized at both December 31, 2016 and December 31, 2015, respectively; 52,665 and 50,346 shares issued and outstanding at December 31, 2016 and December 31, 2015, respectively	5	5
Additional paid in capital	453,044	436,259
Accumulated deficit	(345,848)	(250,083)
Accumulated other comprehensive loss	(725)	(1,416)
Total stockholders' equity	106,476	184,765
Total liabilities and stockholders' equity	$ 210,680	$ 265,240

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Consolidated Balance Sheets
Allowances on accounts receivable	$ 1,890	$ 971
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	52,665,000	50,346,000
Common stock, shares outstanding	52,665,000	50,346,000

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Product revenues	$ 213,968	$ 188,168	$ 157,308
Licensing and other revenues	3,106	2,187	1,981
Total revenues	217,074	190,355	159,289
Cost and expenses
Cost of product, licensing and other revenues	135,574	112,845	78,396
Research and development	41,862	27,711	17,292
Selling, general and administrative	136,126	109,637	62,936
Total cost and expenses	313,562	250,193	158,624
(Loss) income from operations	(96,488)	(59,838)	665
Interest expense	(533)	(3,505)	(4,219)
Interest benefit from changes in the fair value of long term debt		964	118
Interest and other income (expense), net	1,398	(7,896)	(1,716)
Loss before income taxes	(95,623)	(70,275)	(5,152)
Income tax expense	(142)
Net loss	(95,765)	(70,275)	(5,152)
Unrealized gain (loss) on available-for-sale securities, net of tax	691	(1,416)
Comprehensive loss	$ (95,074)	$ (71,691)	$ (5,152)
Basic and diluted net loss per share (in dollars per share)	$ (1.86)	$ (2.68)	$ (1.07)
Weighted-average number of shares used in computing basic and diluted net loss per share	51,576	26,204	4,800

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Common stock	Additional Paid-in Capital	Notes Receivable from Officers	Accumulated Other Comprehensive Loss	Accumulated Deficit	Total
Balance at Dec. 31, 2013	$ 1	$ 3,338	$ (192)		$ (174,656)	$ (171,509)
Balance (in shares) at Dec. 31, 2013	6,561
Issuance of common stock upon exercise of stock options		169				169
Issuance of common stock upon exercise of stock options (in shares)	318
Stock based compensation		5,157				5,157
Net loss					(5,152)	(5,152)
Balance at Dec. 31, 2014	$ 1	8,664	(192)		(179,808)	(171,335)
Balance (in shares) at Dec. 31, 2014	6,879
Issuance of common stock upon exercise of stock options		1,258				1,258
Issuance of common stock upon exercise of stock options (in shares)	1,170
Stock based compensation		7,326				7,326
Officer loan receivable repayment			$ 192			192
Issuance of common stock in connection with the initial public offering	$ 1	182,465				182,466
Issuance of common stock in connection with the initial public offering (in shares)	10,900
Issuance costs of Initial Public Offering		(4,036)				(4,036)
Conversion of all Preferred Stock into Common Stock upon the completion of the initial public offering	$ 3	240,582				240,585
Conversion of all Preferred Stock into Common Stock upon the completion of the initial public offering (in shares)	31,397
Unrealized gain (loss) on available-for-sale investments				$ (1,416)		(1,416)
Net loss					(70,275)	(70,275)
Balance at Dec. 31, 2015	$ 5	436,259		(1,416)	(250,083)	$ 184,765
Balance (in shares) at Dec. 31, 2015	50,346					50,346
Issuance of common stock upon exercise of stock options		3,595				$ 3,595
Issuance of common stock upon exercise of stock options (in shares)	1,913
Issuance of common stock under employee stock purchase plan		2,589				2,589
Issuance of common stock under employee stock purchase plan (in shares)	341
Vesting of restricted stock (in shares)	65
Stock based compensation		10,601				10,601
Unrealized gain (loss) on available-for-sale investments				691		691
Net loss					(95,765)	(95,765)
Balance at Dec. 31, 2016	$ 5	$ 453,044		$ (725)	$ (345,848)	$ 106,476
Balance (in shares) at Dec. 31, 2016	52,665					52,665

Consolidated Statements of Con6

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Temporary Equity) - 12 months ended Dec. 31, 2014 - USD ($) shares in Thousands	Convertible preferred stock	Total
Convertible preferred stock balance at Dec. 31, 2013	$ 185,199,000
Convertible preferred stock balance (in shares) at Dec. 31, 2013	27,048
Issuance of convertible preferred stock	$ 55,413,000
Issuance of convertible preferred stock (in shares)	4,349
Issuance costs of Series F Preferred Stock		$ (86,933)
Convertible preferred stock balance at Dec. 31, 2014	$ 240,612,000	$ 240,612
Convertible preferred stock balance (in shares) at Dec. 31, 2014	31,397

Consolidated Statements of Con7

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical)	12 Months Ended
	Dec. 31, 2014USD ($)$ / shares
Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit)
Preferred stock (in dollars per share) | $ / shares	$ 12.76
Preferred stock issuance costs | $	$ 86,933

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net loss	$ (95,765)	$ (70,275)	$ (5,152)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	6,176	5,535	5,148
Amortization of premium on investment securities	1,445	288
Gain realized on investment securities	(191)
Impairment of assets	2,138	1,557
Inventory excess adjustments	2,110
Stock based compensation	10,601	7,326	5,157
Loss from changes in fair value of warrants	143	1,481	1,664
Provision for doubtful accounts	984	529	349
Non-cash interest accrual	533
(Gain) loss on sales of property and equipment		(2)	11
Amortization of debt discount		28
Gain from change in fair value of long term debt		(964)	(118)
Loss on debt extinguishment		7,313
Changes in operating assets and liabilities
Accounts receivable	(8,518)	(450)	341
Inventory	(431)	2,929	(890)
Prepaid expenses and other current assets	(2,077)	(3,797)	(137)
Restricted cash	150	(273)
Other assets	(2,812)	(1,041)	(24)
Accounts payable	1,256	1,354	(2,430)
Income taxes payable			(15)
Accrued compensation	2,515	2,572	2,994
Other accrued liabilities	7,411	8,026	4,450
Deferred revenue	430	32	(858)
Net cash (used in) provided by operating activities	(73,902)	(37,832)	10,490
Investing Activities
Purchases of investments	(53,522)	(203,290)
Proceeds from sale of investments	59,185
Proceeds from maturity of investments	64,500
Proceeds from sale of property and equipment		463	15
Purchases of property and equipment, net	(23,136)	(7,852)	(9,957)
Net cash (used in) investing activities	47,027	(210,679)	(9,942)
Financing Activities
Proceeds from issuance of common stock, net of issuance costs		180,001	170
Proceeds from exercise of stock options	3,595	1,258
Proceeds from issuance of common stock under employee stock purchase plan	2,589
Proceeds from issuance of preferred stock, net			55,413
Borrowings under credit facility	8,000
Repayment under credit facility	(1,000)
Costs paid for loan		(6)
Proceeds from short-term financing		42,000
Proceeds from equipment financing			5,105
Repayments of equipment financing		(5,850)	(2,480)
Repayments of secured financings		(20,000)
Proceeds from collection of officer receivable		192
Payment to lender for debt extinguishment		(7,313)
Change in restricted cash			(415)
Deferred offering costs			(1,661)
Net cash provided by financing activities	13,184	190,282	56,132
Net (decrease) increase in cash	(13,691)	(58,229)	56,680
Cash at beginning of period	28,947	87,176	30,496
Cash at end of period	15,256	28,947	87,176
Supplemental disclosure of cash flow information:
Cash paid for interest		2,060	2,063
Purchases of property and equipment through accounts payable and accruals	$ 5,204	765	$ 3,223
Conversion of convertible preferred stock to common stock		$ 240,585

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2016
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 genetic disease worldwide. 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 has only one operating segment, which is the discovery, development and commercialization of genetic testing services, and it 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 typically with a blood draw from the mother; Horizon Carrier Screening ("Horizon") 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 Genetic Screening ("PGS") and Spectrum Pre-implantation Genetic Diagnosis ("PGD") to analyze chromosomal anomalies or inherited genetic conditions during an in vitro fertilization ("IVF") cycle to select embryos with the highest probability of becoming healthy children; Anora Products of Conception ("POC") test to rapidly and extensively analyze fetal chromosomes to understand the cause of miscarriage; Non-Invasive Paternity Testing ("PAT"), to determine paternity by analyzing the fragments of fetal deoxyribonucleic acid ("DNA") in a pregnant mother's blood and a blood sample from the alleged father(s), which is marketed and sold exclusively by a licensee from whom the Company receives a royalty. All testing is available principally in the United States and Europe. The Company also offers Constellation (“Constellation”), a cloud-based software product that allows laboratory customers to gain access through the cloud to the Company’s algorithms and bioinformatics in order to validate and launch tests based on the Company’s technology. Initial Public Offering In July 2015, the Company completed an initial public offering (“IPO”), and subsequently in August 2015, the Company completed the sale of additional shares upon exercise of the underwriters’ over-allotment option. In connection with the IPO, including the over-allotment option, the Company sold 10,900,000 shares of common stock at $18.00 per share, which raised $178.5 million in proceeds, net of underwriting discounts and commissions and offering expenses.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2 . Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”). Need to Raise Additional Capital The Company has incurred net losses since its inception and anticipates net losses and negative operating cash flows for the near future. For the year ended December 31, 2016, the Company had a net loss of $95.8 million, and as of December 31, 2016, it had an accumulated deficit of $345.9 million. At December 31, 2016, the Company had $15.3 million in cash and cash equivalents, $130.9 million in marketable securities, and $49.6 million of outstanding debt with accrued interest. While the Company has introduced multiple products that are generating revenues, these revenues have not been sufficient to fund all operations. Accordingly, the Company has funded the portion of operating costs that exceeds revenues through a combination of equity issuances, debt issuances, and other financings. The Company expects 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 would 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 require 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, commercialization and marking of its products and significantly scale back its business and operations. Based on our current business plan, we believe that our existing cash and marketable securities will be sufficient to meet our anticipated cash requirements for at least 12 months after March 16, 2017. Principles of Consolidation The accompanying condensed consolidated financial statements include all the accounts of the Company and its subsidiary. The Company established a subsidiary that operates in the state of Texas in December 2014 to support the Company’s laboratory and operational functions, which became active in the second quarter of 2015. All intercompany balances and transactions have been eliminated. Use of Estimates The preparation of financial statements in accordance with U.S. GAAP 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, accrued liability for potential refund requests, stock-based compensation, the fair value of common stock and fair value of debt accounted for under ASC 815, as well as income tax uncertainties. 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; however, actual results could differ from these estimates and could have an adverse effect on the Company's financial statements. Fair Value The Company discloses the fair value of financial instruments for financial assets and liabilities for which the value is practicable to estimate. Fair value is defined as the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The Company carried senior secured term loan and warrants at fair value according to the fair value measurement guidance. Cash and Cash Equivalents Cash and cash equivalents consist of cash and money market deposits with financial institutions. Restricted Cash The Company discloses both short-term and long-term restricted cash. Short-term restricted cash consists of $1.1 million, which secured a $0.8 million letter of credit for the sublease of the First Space (defined in Note 6) that expired in October 2016, however, the associated restriction has not been released as of December 31, 2016, and a $0.3 million letter of credit for the sublease of the Second Space (defined in Note 6), which expired in January 2017. Long-term restricted cash consists of $0.3 million deposit per credit card terms. Investments Management determines the appropriate classification of securities at the time of purchase and reevaluates 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, even though the stated maturity may be more than one year from the current balance sheet date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive loss, which is a separate component of stockholders’ equity. Risk and Uncertainties 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 bills third-party payers for certain tests performed. The amount that is ultimately received from the payer for the Company’s claim and the timing of such payments are subject to the determination of the payer based on the nature of the test performed and their view of the Company’s business practices with respect to collections of plan deductibles and co-payments from patients and other activities. This determination can impact both the amount and timing of when the Company’s invoices are collected. Payers may also withhold payments and request refunds of prior payments if the Company does not perform in accordance with the policies of these payers. The Company performs evaluations of financial conditions for clinics and laboratory partners and generally does not require collateral to support credit sales. For 2016, 2015 and 2014, there were no customers exceeding 10% in total revenue. As of December 31, 2016, one customer had an outstanding balance of approximately 52% of net accounts receivable, and as of December 31, 2015, no customers had an outstanding balance greater than 10% of net accounts receivable. Allowance for Doubtful Accounts Trade accounts receivable are recorded at the amount billed to the laboratory partners and clinics. Reducing this amount is an allowance for doubtful accounts for estimated losses resulting from the inability of its customers to make the contracted payments. Management analyzes accounts receivable and historical bad debt experience, customer creditworthiness, current economic trends, and changes in customer payment history when evaluating the adequacy of the allowance for doubtful accounts. Accounts receivable are written off against the allowance when there is substantive evidence that the account will not be paid. Revenue Recognition The Company generally bills an insurance carrier, a clinic or a patient for the test upon delivery of the test result. The Company also bills patients directly for out-of-pocket costs not covered by their insurance carriers representing co-pays and deductibles in accordance with their insurance carrier and health plans. For tests performed, where an agreed upon reimbursement rate or fixed fee and a predictable history or likelihood of collections exists, the Company recognizes revenues upon delivery of the test report to the prescribing physician based on the established billing rate less contractual and other adjustments, such as an allowance for doubtful accounts, to arrive at the amount that the Company expects to collect. In all other situations, as the Company does not have sufficient history of collection and is not able to determine collectability, the Company recognizes revenues when cash is received. The Company may not get reimbursed for tests completed if the tests are not covered under the insurance carrier’s reimbursement policies or the Company is not a qualified provider to the insurance carrier. From time to time, the Company receives requests for refunds of payments previously made by insurance carriers. The Company has established an accrued liability for potential refund requests based on its experience, which is accounted for as reductions in revenues in the statement of operations and comprehensive loss. In cases where the Company sells its tests through its laboratory partners, the majority of the laboratory partners bill the patient, clinic, or insurance carrier for the performance of the Company's tests. For tests sold through a limited number of its laboratory partners, the Company bills directly to a patient, clinic or insurance carrier, or a combination of the insurance carrier and patient for the fees. The Company considers its services rendered when it delivers reports of its test results to the laboratory partner, clinic or patient. When the Company has contracted fixed rates for its services and collectability of its revenues is reasonably assured, it recognizes revenues upon delivery of test reports. The fixed fees identified in contracts with laboratory partners change only if a pricing amendment is agreed upon between both parties. For cases in which there is no fixed price established with a laboratory partner, the Company then recognizes revenues from partner distributed tests on a cash basis. Certain of the Company's arrangements include multiple deliverables. For revenue arrangements with multiple deliverables, the Company evaluates each deliverable to determine whether it qualifies as a separate unit of accounting. This determination is based on whether the deliverable has "stand-alone value" to the customer and whether a general right of return exists. The consideration that is fixed or determinable is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. The consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. The Company uses judgment in identifying the deliverables in its arrangements, assessing whether each deliverable is a separate unit of accounting, and in determining the best estimate of selling price for certain deliverables. The Company also uses judgment in determining the period over which the deliverables are recognized in certain of its arrangements. Any amounts received that do not meet the criteria for revenue recognition are recorded as deferred revenue until such criteria are met. The Company receives royalty revenue through the licensing and the provisioning of services to support the use of the Company's proprietary technology with its customer. Royalty revenues are recognized when earned under the terms of the related agreements and are included in licensing and other revenues in the statements of operations and comprehensive loss. The Company recognizes revenue from the cloud-based distribution service offering. The Company grants its customers licenses to use the Company’s proprietary intellectual properties and the cloud-based Natera software, and provides the other services to support the use of the Company's proprietary technology with its customers. Natera’s proprietary software is used in connection with the analysis of DNA sequence data in a manner yielding a result indicating the likely presence or absence of full or partial chromosomal abnormalities. The licensees do not have the right to possess Natera software, but rather are treated as software as a service. The revenues are recognized on an accrual basis (assuming all revenue recognition criteria are met) under the terms of the related agreements and are included in licensing and other revenues in the statements of operation and comprehensive loss. Cost of Product, Licensing and Other Revenues Cost of product, licensing and other revenues includes the cost of materials, direct labor of laboratory personnel, equipment and infrastructure expenses associated with processing blood and other samples, quality control analyses, and shipping charges to transport samples and specimens from ordering physicians, clinics or individuals. Infrastructure expenses include allocated facility and related occupancy costs. Costs associated with the performance of diagnostic services are recorded as tests are processed. Research and Development The Company records research and development costs in the period incurred. Research and development costs consist of personnel costs, contract services, cost of materials utilized in performing tests, costs of clinical trials and allocated facilities and related overhead expenses. Advertising Costs The Company expenses advertising costs as incurred. The Company incurred advertising costs of $0.4 million, $1.1 million and $1.1 million for the years ended December 31, 2016, 2015 and 2014, respectively. Product Shipment Costs The Company expenses product shipment costs in cost of product, licensing and other revenues in the accompanying statements of operations. Shipping and handling costs for the years ended December 31, 2016, 2015 and 2014 were $8.2 million, $7.0 million and $4.5 million, respectively. Income Taxes Income taxes are recorded in accordance with Financial Accounting Standards Board ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Tax benefits are recognized when it is more likely than not that a tax position will be sustained during an audit. Deferred tax assets are reduced by a valuation allowance if current evidence indicates that it is considered more likely than not that these benefits will not be realized. Stock‑Based Compensation Stock‑based compensation related to stock options and restricted stock units (“RSUs”) granted to the Company’s employees 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. No compensation cost is recognized on stock options for employees who do not render the requisite service and therefore forfeit their rights to the stock options. The Company uses the Black‑Scholes option‑pricing model to estimate the fair value of its stock options. The Company accounts for stock options issued to non-employees based on the estimated fair value of the awards using the Black-Scholes option-pricing model. The measurement of stock-based compensation is subject to periodic adjustments as the underlying equity instruments vest, and the resulting change in value, if any, is recognized in the Company's statements of operations and comprehensive loss during the period that the related services are rendered. The Black-Scholes option-pricing model requires the input of the Company's expected stock price volatility, the expected term of the awards, a risk-free interest rate, and expected dividends. Determining these assumptions requires significant judgment. The expected term was based on the simplified method and where the Company did not qualify to use the simplified method, the Company used the lattice model, and the volatility rate was based on that of publicly traded companies in the DNA sequencing, diagnostics, or personalized medicine industries. When selecting the public companies in these industries to be used in the volatility calculation, companies were selected with comparable characteristics to the Company, including enterprise value and financial leverage. Companies were also selected with historical share price volatility sufficient to meet the expected term of the Company's stock options. The historical volatility data was computed using the daily closing prices for the selected companies' shares during the equivalent period of the calculated expected term of the Company's stock options. The expected term of the non-employee option grants was based on their remaining contractual life at the measurement date. The risk-free interest rate assumption was based on U.S. Treasury instruments with maturities that were consistent with the option's expected term. The expected dividend assumption was based on the Company's history and expectation of dividend payouts. Starting January 1, 2016, the Company uses a different approach to estimate the expected term of its stock option awards, which involves calculating the average of—(1) its employees’ historical stock option exercise behavior, and (2) the weighted-average of the time-to-vesting and the total contractual life of the options. The Company applied this change in methodology prospectively and accounted for it as a change in accounting estimate. Warrants The Company accounts for warrants to purchase shares of its common stock as a liability at fair value on the balance sheet date because the Company may be obligated to redeem these warrants at some point in the future. The warrants are subject to remeasurement at each balance sheet date, with changes in fair value recognized as a gain or loss from the changes in fair value of the warrants in the statements of operations. The Company will continue to adjust the liability for changes in fair value until such time that the warrants are converted or expire. Capitalized Software Held for Internal Use The Company capitalizes costs of software held for internal use during the application development stage of a project and amortize those costs over their estimated useful lives of three years. The net book value of capitalized software held for internal use was $1.3 million and $0.8 million as of December 31, 2016 and 2015, respectively. Amortized expense for amounts previously capitalized for the years ended December 31, 2016 and 2015 was $0.6 million and $0.2 million, respectively. There was no amortization of such capitalized costs for the year ended December 31, 2014. Accumulated Other Comprehensive 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. As of December 31, 2016, and 2015, accumulated other comprehensive loss consisted of $0.7 million and $1.4 million of unrealized losses on available-for-sale marketable securities. There was $0.2 million reclassified out of accumulated other comprehensive loss during the year ended December 31, 2016, and no reclassifications were made in the years ended December 31, 2015 and 2014. Property and Equipment Property and equipment, including purchased and internally developed software, are stated at cost. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, which are generally three years. Leasehold improvements are amortized using the straight-line method over the estimated useful lives of the assets or the remaining term of the lease, whichever is shorter. The Company periodically reviews the depreciable lives assigned to property and equipment placed in service and change the estimates of useful lives to reflect the results of such reviews. During the third and fourth quarters of 2016, the Company performed an assessment on its estimated use of certain sequencing and automation equipment. As a result of the assessment, it was determined that the service lives of several of such equipment over which the remaining economic benefit was to be received from were significantly shorter than initially expected by the Company. Additionally, the Company wrote off the remaining maintenance service contract associated with the equipment described above. The Company accounted for the revision of its depreciation estimates on the sequencing and automation equipment and the write off of the unamortized prepaid maintenance as a change in accounting estimate, which increased its loss from operations and net loss by $1.7 million, and increased its basic and diluted net loss per share by $0.04 for the year ended December 31, 2016. During the second quarter of 2015, the Company increased the depreciable lives of certain sequencing and automation equipment from three years to five years. The effect of this change in estimate for the year ended December 31, 2015 was a decrease in loss from operations and net loss of $1.7 million, and a decrease in basic and diluted net loss per share of $0.07. Impairment of Long-lived Assets The Company evaluates its long-lived assets for indicators of possible impairment when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. The Company then compares the carrying amounts of the assets with the future net undiscounted cash flows expected to be generated by such asset. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s fair value determined using discounted estimates of future cash flows. For the years ended December 31, 2016 and 2015, we recorded asset impairment losses of $2.1 million and $1.6 million, respectively. See Note 5 for more detail about the asset impairment. Inventory Inventory is valued at the lower of the standard cost, which approximates actual cost, or market. Cost is determined using the first-in, first-out ("FIFO") method. Inventory consists entirely of supplies, which are consumed when providing its test reports, and therefore does not maintain any finished goods inventory. The Company enters into inventory purchases and commitments so that it can meet future delivery schedules based on forecasted demand for its tests. In December 2016, the Company determined $2.1 million of inventory as obsolete in connection with its impairment analysis of the associated automation and sequencing equipment described above, and recorded an associated charge for these materials. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or FASB 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 recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In August 2014, FASB issued Accounting Standards Update No. 2014‑15 (“ASU 2014-15”), Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern . ASU 2014‑15 requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. ASU 2014‑15 is effective for the Company in the first quarter of 2017 with early adoption permitted. The Company has elected to early adopt this guidance for its annual reporting period ending December 31, 2016, and this ASU applies to all future annual and interim reporting periods. Upon adoption, the Company is required to perform assessment using detailed prospective financial information during each interim period and annually to determine whether substantial doubt exists about its ability to continue as a going concern for at least 12 months from the issuance date of the financial statements, and to provide the related disclosures. As a result of the analysis, the adoption of ASU 2014‑15 did not have a material impact on the Company’s financial statements and related disclosures, although the related disclosures could be impacted in future periods. In May 2014, FASB issued Accounting Standards Update No. 2014-09 (“ASU 2014-09”), Revenue from Contracts with Customers to provide guidance on revenue recognition. To date, the Company’s revenues have been derived primarily from contracts with insurance carriers, patients, clinics and licensing arrangements. Approximately 82% of the Company’s revenues are recognized on the cash basis, and based on the Company’s preliminary assessment, this portion of revenues may be recognized at an earlier date than in the period of actual cash receipt. Consideration is received from either patients, clinics, or insurance carriers and/or any combination of the three, and licensees. Each one of these arrangements, whether sell-in or sell-through, is considered unique and being evaluated individually under the five-step process prescribed by the new revenue standard. Currently, the Company continues to assess its contracts with insurance carriers. The Company has not completed its analysis, and it is evaluating whether the impact of adopting ASU 2014-09 will be material to its financial statements. ASU 2014-09 will be effective for the Company in the first quarter of 2018, with early adoption permitted starting the first quarter of 2017. Upon adoption, ASU 2014-09 can be applied retrospectively to all periods presented or using the modified retrospective approach, which requires the cumulative effect of changes reflected in the opening balance of retained earnings only in the most current period presented. The Company has not yet determined which method will be used upon adoption, and will plan on adopting the new guidance in the first quarter of 2018. In July 2015, FASB issued Accounting Standards Update No. 2015-11 (“ASU 2015-11”), Inventory (Topic 330): Simplifying the Measurement of Inventory (ASU 2015-11). ASU 2015-11 simplifies the subsequent measurement of inventory by replacing today’s lower of cost or market test with a lower of cost and net realizable value test. ASU 2015-11 is effective for the Company in the fiscal year beginning after December 15, 2016, and interim periods within those fiscal years. The Company does not expect the adoption of ASU 2015‑11 will have a material impact on its financial statements. In November 2015, FASB issued Accounting Standards Update No. 2015-17 (“ASU 2015-17”), Balance Sheet Classification of Deferred Taxes , which simplifies the presentation of deferred taxes by requiring that deferred tax assets and liabilities be presented as noncurrent on the balance sheet. ASU 2015-17 is effective for the Company in the fiscal year beginning after December 15, 2016, and interim periods within those fiscal years. The Company currently does not have any deferred tax assets or liabilities on its balance sheet as a full valuation allowance has been reserved against them, and it does not expect the adoption of ASU 2015-17 will have a material impact on its financial statements. In February 2016, the FASB issued Accounting Standards Update No. 2016-02 (“ASU No. 2016-02”), Leases . ASU 2016-02 is aimed at making leasing activities more transparent and comparable, and requires substantially all leases be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. ASU 2016-02 is effective for the Company in the fiscal year beginning after December 15, 2018, and interim periods within those fiscal years with early adoption permitted. The Company plans to adopt this new guidance prospectively in the first quarter of 2019. The Company is evaluating the impact of the adoption of this guidance on its financial statements, and expects that it will increase our lease assets and correspondingly increase our lease liabilities. In March 2016, the FASB issued Accounting Standards Update No. 2016-09 (“ASU 2016-09”), Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. ASU 2016-09 includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. The new guidance requires any excess tax benefits (“windfalls”) and tax deficiencies (“shortfalls”) associated with vested or settled share-based awards to be recognized in the income statement rather than additional paid-in capital, which is to be applied prospectively. Further, windfalls will be required to be presented as an operating activity rather than as an outflow from operating activity and an inflow to financing activity, as required by the existing guidance. This new presentation guidance can be applied retrospectively or prospectively. The new guidance also eliminates the requirement to delay the recognition of windfalls until it begins to reduce current income taxes payable, and this is to be applied using the modified retrospective approach, with a cumulative effect adjustment to opening retained earnings. In addition, ASU 2016-09 allows entities to withhold an amount up to the employees’ maximum individual tax rate in the relevant jurisdiction without having to account for the award as a liability-based award, and this guidance is to be applied using the modified retrospective approach, with a cumulative effect adjustment to opening retained earnings. ASU 2016-09 also permits forfeitures to be either estimated, as required by the existing guidance, or recognized when they occur. The change in the accounting for forfeitures is required to be applied using a modified retrospective approach, with a cumulative effect adjustment to opening retained earnings. The new guidance will be effective for public entities in fiscal years beginning after December 15, 2016. The Company plans to adopt this new guidance in the first quarter of 2017 and does not expect a material impact on its financial statements given the full valuation allowance position on its deferred tax assets. In August 2016, the FASB issued Accounting Standards Update No. 2016-15 (“ASU 2016-15”), Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (A Consensus of the Emerging Issues Task Force). The purpose of ASU 2016-15 is to limit diversity in the classification of certain transactions in the statement of cash flows. Such transactions include (1) debt prepayment or debt extinguishment costs, (2) settlement of zero-coupon bonds, (3) contingent consideration payments made after a business combination, (4) proceeds from insurance claims settlement, (5) proceeds from settlement of life insurance policies, and (6) distributions of equity method investments. ASU 2016-15 will be effective for the Company in the fiscal year beginning after December 15, 2017, and interim periods within that fiscal year. The Company is currently evaluating the impact of adopting ASU 2016-15 on its financial statements. In November 2016, the FASB issued Accounting Standards Update No. 2016-18 (“ASU 2016-18”), Statement of Cash Flows (Topic 230): Restricted Cash. The purpose of ASU 2016-18 is to eliminate the diversity in classifying and presenting changes in restricted cash in the statements of cash flows. The new guidance requires restricted cash to be combined with cash and cash equivalents when reconciling the beginning and ending balances of cash on the statement of cash flows, thereby no longer requiring transactions such as transfers between restricted and unrestricted cash to be treated as a cash flow activity. Further, the new guidance requires the nature of the restrictions to be disclosed, as well as a reconciliation between the balance sheet and the statement of cash flows on how restricted and unrestricted cash are segregated. The new guidance will be effective for the Company in the fiscal year beginning after December 15, 2017, and interim pe

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Measurements
Fair Value Measurements	3. 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, a liability for convertible preferred stock warrants and a liability for common stock warrants. The Company’s Credit Line described in Note 8, is not measured at fair value on a recurring basis and is carried at amortized cost. The Company believes that the fair value of the Credit Line approximates its carrying value or amortized costs, due to the short-term nature of this obligation and the interest rate relative to market rates. 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. There were no transfers between Level I, Level II and Level III during the periods presented. Assets and Liabilities That Are Measured at Fair Value on a Recurring Basis The following table represents the fair value hierarchy for the Company’s financial assets and financial liabilities measured at fair value on a recurring basis: December 31, 2016 December 31, 2015 Level I Level II Level III Total Level I Level II Level III Total (in thousands) Financial Assets: Money market deposits $ $ — $ — $ $ $ — $ — $ U.S. Treasury securities — — — — U.S. agency securities — — — — Municipal securities — — — — Total financial assets $ $ $ — $ $ $ $ — $ Current Liabilities: Warrants $ $ — $ $ $ — $ — $ $ Total financial liabilities $ — $ — $ $ $ — $ — $ $ The Company's warrants to purchase common stock are valued using Level III inputs; the Company used inputs from a Black-Scholes model with market volatility that is determined for comparable companies in the same business sector. The carrying amounts of cash, accounts receivable, and accounts payable approximate their fair value and are excluded from the table above. In April 2013, the Company entered into a senior secured term loan with a third‑party lender, which consisted of a credit agreement, royalty agreement, warrants, and loan commitment. The Company considered the guidance under ASC 825‑10, Financial Instruments , which provides a measurement basis election for most financial instruments (i.e., either historical cost or fair value), allowing reporting entities to mitigate potential mismatches that arise under the current mixed measurement attribute model and ASC 820, Fair Value Measurements and Disclosures that provides for the fair value measurement of assets and liabilities, except for derivatives, for which the fair value is determined by ASC 815, Derivatives and Hedging . The Company evaluated the components of the senior secured term loan and determined that they were derivatives to be evaluated under ASC 815‑15‑25‑1. The fair value accounting for derivatives is not an option, as derivatives must be fair valued under ASC 815 following the measurement guidance under ASC 820. Therefore, the Company engaged a third party to determine the fair value of the derivatives using the guidance of ASC 820 and recorded the senior secured term loan at fair value. ASC 815 requires the terms and features of an instrument that are not a derivative itself to be evaluated for embedded derivatives that must be bifurcated and separately accounted for as freestanding derivatives, provided that certain criteria of ASC 815 are met. As a result of the Company's evaluation, it was indicated that the senior secured term loan constituted a liability with embedded derivative features, which were accounted for separately as mark-to-market instruments. As for the warrants that were granted with this senior secured term loan, it was determined that they were detachable and therefore a stand-alone component of the senior secured term loan which was to be fair valued using Level III inputs as a separate derivative. Determining the fair value of these instruments required significant judgment or estimation, and the Company utilized various techniques such as (i) discounted future cash flows, (ii) the income approach, using various revenue assumptions and applying a Monte-Carlo Simulation to each outcome and (iii) Black-Scholes Option Pricing Model with market volatility that was determined by comparison to comparable companies in the same business sector. The fair value of both the senior secured term loan and warrants was re-measured at the end of each reporting period with the change in fair value recorded within non-operating expense in the statements of operations and comprehensive loss. In October 2015, the Company repaid the entire borrowings under the senior secured term loan. The following table provides a roll forward of the fair value, as determined by Level III inputs, of the warrants for the years ended December 31, 2016 and 2015: Warrants 2016 2015 (in thousands) Beginning balance $ $ Warrants exercised — Change in fair value Ending balance $ $ The following table provides a roll forward of the fair value, as determined by Level III inputs, of the senior secured term loan for the years ended December 31, 2016 and 2015: Term Loan 2016 2015 (in thousands) Beginning balance $ — $ Change in fair value recognized in non-operating expense — Loan payment — Ending balance $ — $ — The following table presents quantitative information about the inputs and valuation methodologies used for the Company’s fair value measurement classified in Level III of the fair value hierarchy at December 31, 2016. Weighted Average Interest on Fair Value at Significant Discount Rate December 31, 2016 Valuation Methodology Unobservable Input (range, if applicable) (in thousands) Warrants $ Black-Scholes Option Pricing Model Volatility % Warrants The significant unobservable inputs used in the fair value of warrants are derived from the Company's common stock valuation that is based upon a model with inputs from a Black-Scholes model and market volatility that is determined for comparable companies in the same business sector. The inherent risk in the market volatility is the selection of companies with similar business attributes to the Company. The Company changed the volatility assumption from a group of 15 companies that was shared with the secured debt volatility prior periods to a group of four companies that is shared with the volatility used for stock-based compensation. The Company determined this was appropriate as the secured debt was settled in October 2015 and results in consistent volatility assumptions used for both common stock warrants and stock-based compensation. This resulted in an increase of the Company’s warrant valuation of $0.1 million on December 31, 2016.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2016
Financial Instruments
Financial Instruments	4. Financial Instruments The Company elected to invest a portion of its cash assets in conservative, income earning, liquid investments effective September 2015. Cash equivalents and investments, all of which are classified as available-for-sale securities, consisted of the following: December 31, 2016 December 31, 2015 Amortized Gross Gross Estimated Fair Amortized Gross Gross Estimated Fair (in thousands) Money market deposits $ $ — $ — $ $ $ — $ — $ U.S. Treasury securities — U.S. agency securities — — Municipal securities — Total $ $ — $ $ $ $ $ $ Classified as: Cash equivalents $ $ Short-term investments Total $ $ The Company invests in U.S. Treasuries, U.S. agency and high quality municipal bonds which mature at par and are all paying their coupons on schedule. Thus, the Company has determined there is currently no other than temporary impairment of our investments, and will continue to recognize unrealized losses and gains in other comprehensive income. For the year ended December 31, 2016, the Company had $0.2 million in realized gains and immaterial realized losses for a total net realized gain of $0.2 million as a result of the sale of investments. There was no sale of investments for the year ended December 31, 2015. As of December 31, 2016, the Company has 27 investments in an unrealized loss position in its portfolio. Available-for-sale debt securities that were in a continuous loss position but were not deemed to be other than temporarily impaired were immaterial as of December 31, 2016. The Company earned interest income of $1.5 million during the year ended December 31, 2016. The following table summarizes the Company’s portfolio of available-for-sale securities by contractual maturity as of December 31, 2016: December 31, 2016 Amortized Fair (in thousands) Less than one year $ $ Greater than one year but less than five years Total $ $

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2016
Balance Sheet Components
Balance Sheet Components	5. Balance Sheet Components Allowance for Doubtful Accounts The following table presents a reconciliation of the allowance for doubtful accounts: December 31, December 31, 2016 2015 (in thousands) Beginning balance $ $ Provision for estimated bad debts Write offs Ending balance $ $ Property and Equipment, net The Company’s property and equipment consisted of the following: December 31, December 31, Useful Life 2016 2015 (in thousands) Machinery and equipment 3-5 years $ $ Furniture and fixtures 3 years Computer equipment 3 years Capitalized software held for internal use 3 years Leasehold improvements Life of lease Construction-in-process Less: Accumulated depreciation and amortization Total Property and equipment, net $ $ All of the Company’s long-lived assets are located in the United States. In September 2015, the Company paid off the Equipment Financing Facility, thus none of the Company's equipment is subject to pledge. The Company periodically evaluates the carrying value of long-lived assets when events or circumstances warrant such a review. The carrying value of a long-lived asset is considered impaired when the estimated realizable value of the asset is less than the carrying value of the asset. In that event, a loss is recognized based on the amount by which the carrying value exceeds the fair value of the long-lived asset. Fair value is determined based on the estimated realizable value of the long-lived asset. The Company recorded asset impairment charges totaling $2.1 million in cost of product, licensing and other revenues in the statements of operations and comprehensive loss during the year ended December 31, 2016 following its impairment analysis on certain sequencing and automation equipment whose service lives were determined to be significantly shorter than initially expected. Total impairment charge of $2.1 million also included the write-off of $0.3 million unamortized maintenance service contract prepayments related to the impaired equipment described above. Those equipment were phased out in January 2017 as the Company began its transition to the next generation of sequencing and automation equipment to help streamline its production workflows. Another impairment charge of $0.2 million was recorded in general and administrative expenses in the statements of operations and comprehensive loss to write off the carrying value of an equipment that was not actively used in production. The Company recorded an asset impairment charge of $1.0 million against a specific group of machinery and equipment during the year ended December 31, 2015. The Company no longer uses this specific group of machinery and equipment because of outsourcing to its partners. The impairment charge was recorded to reflect reductions in the estimated realizable value of the machinery and equipment as a result of planning for its sale in the secondary market. The Company recorded the total impairment charge of $1.0 million in cost of product, licensing and other revenues. The Company sold some of the impaired machinery and equipment during the fourth quarter of 2015 for $0.5 million and classified the remaining impaired machinery and equipment as held for sale at the estimated realizable value of $0.2 million. The remaining impaired machinery was sold in January 2016 for $0.2 million. Other Assets In April 2016, the Company entered into a four-year agreement with an insurance carrier whereby in return for partial exclusivity and the right to pricing benefits the Company paid total consideration of $3.2 million. As of December 31, 2016, $2.6 million in deferred costs was included in other assets. The deferred costs are being amortized ratably over the four-year term of the agreement. During the year ended December 31, 2016, the Company has amortized $0.6 million of the deferred costs, which was recorded as a reduction of product revenues in the statements of operations and comprehensive loss. Accrued Compensation The Company’s accrued compensation consisted of the following: December 31, December 31, 2016 2015 (in thousands) Accrued paid time off $ $ Accrued commissions Accrued bonuses Other accrued compensation Total accrued compensation $ $ Other Accrued Liabilities The Company’s other accrued liabilities consisted of the following: December 31, December 31, 2016 2015 (in thousands) Overpayments from insurance carriers $ $ Other accrued expenses Testing and laboratory materials from suppliers Marketing and corporate affairs Leasehold improvement projects in progress — Accrued specimen service fees Accrued shipping charges Sales tax payable Clinical trials and studies Accrued rent Legal, audit and consulting fees Deferred lease obligation — Total other accrued liabilities $ $

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies
Commitments and Contingencies	6. Commitments and Contingencies Operating Leases As of December 31, 2016, the Company sub‑leases office facilities under non‑cancelable operating lease agreements. The Company occupies approximately 88,000 square feet of laboratory and office space at our corporate headquarters in San Carlos, California pursuant to two separate subleases. One sublease covers approximately 61,000 square feet (the “First Space”), and the other sublease covers approximately 27,000 square feet (the “Second Space”). In connection with the sublease for the First Space in January 2013 and the Second Space in March 2014, the Company executed two letters of credit in favor of the lessors for $0.8 million and $0.3 million, respectively. In October 2016, the Company amended the lease agreement that it directly entered into with the landlord of our First Space and Second Space (as described above) to include a sublease of additional office space to accommodate its growth and consolidate its operations in California at one location. The additional sublease covers approximately 48,000 square feet of office space and consists of two phases. The first phase began in October 2016 and covers approximately 16,000 square feet of office space at a base rent of $60,730 per month. The second phase began in January 2017, which covers approximately 32,000 square feet of office space at a base rent of $121,460 per month. The term of this sublease is approximately eighty-four months, with the same expiration date as the First Space and Second Space, which is in October 2023. In April 2015, the Company entered into a sub-lease agreement for additional office space in Redwood City, California. The additional space carried a base rent of $0.1 million per month. The lease period began in June 2015 and terminated in August 2016 with no option to extend the lease. In addition, the Company paid a security deposit of $0.1 million. In September 2015, the Company’s subsidiary entered into a long-term lease agreement for laboratory and office space totaling approximately 94,000 square feet in Austin, Texas. The lease term is 132 months beginning in December 2015 with monthly payments beginning in December 2016, increasing from $0.1 million to $0.2 million. Pursuant to the terms of the lease, the subsidiary has paid a security deposit of $0.4 million, and the landlord has allotted the subsidiary an allowance for leasehold improvements of up to $7.8 million. As of December 31, 2016, a total of $5.4 million of the allowance has been reimbursed by the landlord. The future annual minimum lease payments under all non-cancelable operating leases as of December 31, 2016 are as follows: Operating Leases (in thousands) Year ending December 31: 2017 $ 2018 2019 2020 2021 2022 and thereafter Total future minimum lease payments $ Rent expense for the years ended December 31, 2016, 2015 and 2014 was $5.4 million, $2.7 million and $1.5 million, respectively. The Company is also required to pay its share of facility operating expenses with respect to the facilities in which it operates. Legal Proceedings From time to time, the Company is involved in disputes, litigation, and other legal actions. The Company is aggressively defending its current litigation matters, and while there can be no assurances and the outcome of these matters is currently not determinable, the Company currently believes that there are no existing claims or proceedings that are likely to have a material adverse effect on its financial position. There are many uncertainties associated with any litigation and these actions or other third-party claims against the Company 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 actual liability in any such matters may be materially different from the Company's estimates, if any, which could result in the need to record or adjust a liability and record additional expenses. 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. On each of February 17, 2016, March 10, 2016, March 28, 2016 and April 4, 2016, purported class action lawsuits were filed in the Superior Court of the State of California for the County of San Mateo (the “San Mateo Superior Court”), against the Company, its directors and certain of its officers and 5% stockholders and their affiliates, and each of the underwriters of the Company’s July 1, 2015 initial public offering (the "IPO"). The complaints assert claims under Sections 11, 12(a)(2) and 15 of the Securities Act of 1933, as amended. The complaints allege, among other things, that the Registration Statement and Prospectus for the Company’s IPO contained materially false or misleading statements, and/or omitted material information that was required to be disclosed, about the Company’s business and prospects. Among other relief, the complaints seek class certification, unspecified compensatory damages, rescission, attorneys' fees, and costs. The Company removed these actions to the United States District Court for the Northern District of California, and the actions were subsequently remanded back to the San Mateo Superior Court. The Company has appealed the remand and moved to stay, or put a hold on, discovery pending the appeal. The Company has also filed a demurrer, or a request for dismissal as a matter of law, in the San Mateo Superior Court, which has not yet been heard. The Company intends to defend the matter vigorously, 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. In light of, among other things, the early stage of the litigations, the Company is unable to predict the outcome and is unable to make a meaningful estimate of the amount or range of loss, if any, that could result from any unfavorable outcome. On March 4, 2016, a lawsuit was filed against the Company in the Superior Court of the State of California for the County of San Diego, by a patient alleging that Natera failed to perform a test that was ordered. The complaint seeks compensatory damages. This matter is in the discovery stage. The Company intends to vigorously defend against the claims in this lawsuit, and assert any counterclaims that may be available to it. The Company cannot provide any assurance as to the ultimate outcome or that an adverse resolution of this lawsuit would not have a material adverse effect on its financial condition and results of operations. In light of, among other things, the early stage of the litigation, the Company is unable to predict the outcome and is unable to make a meaningful estimate of the amount or range of loss, if any, that could result from any unfavorable outcome. On December 12, 2015, the Company received a civil investigative demand from the United States Department of Justice in connection with what the Company understands to be a qui tam action related to the billing of some of its testing, brought by a former employee. The Company has produced documents in response to the demand. An adverse ruling in this proceeding could require the Company to pay treble damages, civil penalties, and attorneys’ fees, costs and expenses, which could materially and adversely affect its business, financial condition and results of operations. The Company has only received a civil investigative demand and has not been served with a complaint; accordingly, the Company is unable to predict the outcome and is unable to make a meaningful estimate of the amount or range of loss, if any, that could result from an unfavorable outcome. On December 9, 2016, the Company filed a lawsuit against Bio-Reference Laboratories, Inc. (“Bio-Reference”) in the U.S. District Court for the Southern District of New York alleging that Bio-Reference breached a licensing and joint development agreement (the “Licensing Agreement”) between Bio-Reference and Natera, misappropriated trade secrets, and converted confidential information. The Company also filed a motion for a temporary restraining order and preliminary injunction enjoining Bio-Reference from launching a nationwide marketing campaign of its product in violation of the Licensing Agreement. On December 10, 2016, the Company’s motion for a temporary restraining order was denied, and the Court ordered both parties to submit proposed hearing dates with respect to our motion for a preliminary injunction. The Company and Bio-Reference have resolved the matter as of February 2017. 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 an $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 In November 2014, a third-party payer sought information as part of an investigative audit of claims which it had paid for certain genetic testing. The Company complied with their request and provided responsive information. In a letter dated June 2, 2015, the third-party payer alleged that it had overpaid $1.9 million to the Company, which it claimed was an overpayment reflecting the difference between what it paid to the Company and what it contended it should have paid based on its fee schedule and coverage determinations. In August 2015, the Company reached an agreement for a settlement payment of $1.2 million as part of a complete settlement of this matter. This charge was recorded against revenue in the second quarter of 2015. In March 2017, a third-party payer alleged that it had overpaid the Company, and has demanded recoupment of the alleged overpayments. The Company disagrees with the contentions. Contractual Commitments As of December 31, 2016, the Company has non‑cancelable contractual commitments with a supplier for approximately $5.1 million and other material supplier commitments for approximately $3.4 million for inventory material used in the laboratory testing process. As of December 31, 2016, the Company has a non-cancelable license agreement with a vendor for approximately $3.0 million. This represents binding and remaining commitments with the vendor through December 31, 2019.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2016
Stock-Based Compensation
Stock-Based Compensation	7. Stock‑Based Compensation Equity Plans 2015 Equity Incentive Plan General . The Company’s board of directors adopted its 2015 Equity Incentive Plan, or the 2015 Plan, in June 2015. The Company’s 2015 Plan replaced its 2007 Stock Plan. However, awards outstanding under the 2007 Plan will continue to be governed by the terms of the 2007 plan. Share Reserve . The initial number of shares of the Company’s common stock available for issuance under the 2015 Plan was 3,451,495 shares. As of December 31, 2016, 13,094,869 shares were reserved for future issuance under the 2015 plan, which includes unissued and forfeited shares from the 2007 plan. The number of shares reserved for issuance under the 2015 Plan will be increased automatically on the first business day of each of our fiscal years, commencing in 2016, by a number equal to the smallest of: · 3,500,000 shares; · 4% of the shares of common stock outstanding on the last business day of the prior fiscal year; or · the number of shares determined by our board of directors. Stock options vest as determined by the compensation committee. In general, they will vest over a four-year period following the date of grant. Stock options expire at the time determined by the compensation committee but in no event more than ten years after they are granted. These awards generally expire earlier if the participant's service terminates earlier. Restricted Shares and Stock Units. Restricted shares and stock units may be awarded under the 2015 Plan in return for any lawful consideration, and participant who receive restricted shares or stock units generally are not required to pay cash for their awards. In general, these awards will be subject to vesting. Vesting may be based on length of service, the attainment of performance-based milestones or a combination of both, as determined by the compensation committee. 2007 Stock Plan General. The Company’s board of directors adopted its 2007 Plan in January 2007, and it was approved by the Company’s stockholders. No further awards have been made under the 2007 Plan after July 1, 2015, the date of the Company’s initial public offering; however, awards outstanding under our 2007 Plan will continue to be governed by their existing terms. Share Reserve . As of December 31, 2016, the Company reserved 7,713,510 shares of its common stock for issuance under the 2007 Plan, all of which may be issued as incentive stock options. As of December 31, 2016, options to purchase 6,098,564 shares of common stock, at exercise prices ranging from $0.0978 to $12.8501 per share, or a weighted-average exercise price of $2.71 per share, were outstanding under the 2007 Plan. Options vest as determined by the administrator. In general, the Company granted options that vest over a four-year period following the date of grant. In most cases, options granted prior to 2011 (and prior to 2012 with respect to the Company’s executive officers) were immediately exercisable, subject to the Company’s right to repurchase unvested shares. Options expire at the time determined by the administrator, but in no event more than ten years after they were granted, and generally expire earlier if the optionee's service terminates earlier. Restricted Shares. Restricted shares could be awarded or sold under the 2007 Plan in return for cash or cash equivalents or, as permitted by the administrator in its sole discretion, in exchange for services rendered to the Company, by delivery of a full-recourse promissory note or through any other means permitted by applicable law. Restricted shares vest as determined by the administrator. 2015 Employee Stock Purchase Plan General . The Company’s 2015 Employee Stock Purchase Plan, or 2015 ESPP, was adopted by its board of directors in June 2015 and its stockholders approved it in June 2015. The 2015 ESPP is intended to qualify under Section 423 of the Internal Revenue Code. Share Reserve. The Company has reserved 893,548 shares of its common stock for issuance under the 2015 ESPP. As of December 31, 2016, 1,056,344 shares were available for issuance under the 2015 plan. The number of shares reserved for issuance under the 2015 ESPP will automatically be increased on the first business day of each of the Company’s fiscal years, commencing in 2016, by a number equal to the least of: · 880,000 shares; · 1% of the shares of common stock outstanding on the last business day of the prior fiscal year; or · the number of shares determined by our board of directors. The number of shares reserved under the 2015 ESPP will automatically be adjusted in the event of a stock split, stock dividend or a reverse stock split (including an adjustment to the per-purchase period share limit). Offering Periods. Each offering period will last a number of months determined by the compensation committee, not to exceed 27 months. A new offering period will begin periodically, as determined by the compensation committee. Offering periods may overlap or may be consecutive. Unless otherwise determined by the compensation committee, two offering periods of six months' duration will begin in each year on May 1 and November 1. The first offering period started on December 15, 2015 and ended on April 30, 2016, and 116,215 shares were purchased at the end of this offering period for a total proceeds of $1.0 million. The second offering period started on May 1, 2016 and ended on October 31, 2016, and 224,637 shares were purchased at the end of this offering period for a total proceeds of $1.6 million. Purchase Price. The price of each share of common stock purchased under our 2015 ESPP will not be less than 85% of the lower of the fair market value per share of common stock on the first day of the applicable offering period (or, in the case of the first offering period, the price at which one share of common stock is offered to the public in this offering) or the fair market value per share of common stock on the purchase date. Early Exercise of Employee Options As of December 31, 2015, the Company had approximately 1.3 million exercised and unvested shares outstanding that are subject to a repurchase right held by the Company at the original issuance price in the event that the optionee’s employment is terminated, either voluntarily or involuntarily. Effective in the year ended December 31, 2015, pursuant to the agreements with the option holders, the Company changed its estimated expiration of its repurchase right for 1.3 million exercised and unvested shares outstanding that are subject to repurchase right held by it through the 210 days after the date of the prospectus filed in connection with the Company’s IPO. Accordingly, the unrecognized compensation expense is being accelerated over a shorter performance period through January 2016. As a result of this acceleration, the Company recorded an additional $1.3 million in stock-based compensation expense during the year ended December 31, 2015. Stock Options The following table summarizes option activity during the year ended December 31, 2016: 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, 2015 $ 8.31 $ Additional shares authorized — Options granted $ Options exercised — $ Options forfeited $ Balance at December 31, 2016 $ 7.55 $ Exercisable at December 31, 2016 $ 6.51 $ Vested and expected to vest at December 31, 2016 $ 7.55 $ The total intrinsic value of stock options exercised during the years ended December 31, 2016, 2015 and 2014 was $16.9 million, $6.9 million and $1.2 million, respectively. The total fair value of stock options vested during the years ended December 31, 2016, 2015 and 2014 was $8.5 million $4.5 million and $4.1 million, respectively. The weighted-average grant date fair value of options granted during the years ended December 31, 2016, 2015 and 2014 was $5.92, $7.29 and $3.28 per share, respectively. Restricted Stock Awards In February 2016, the Company granted 24,540 fully vested restricted shares to a non-employee service provider. Restricted Stock Units Starting April 2016, the Company began granting restricted stock units to its employees from the 2015 Plan. The following table summarizes restricted stock unit activity for the year ended December 31, 2016: Weighted-Average Grant Date Shares Fair Value Balance at December 31, 2015 — $ — Granted $ Vested $ Canceled/forfeited $ Balance at December 31, 2016 $ Stock‑Based Compensation Expense Employee and non‑employee stock‑based compensation expense was calculated based on awards ultimately expected to vest and have 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. The following table presents the effect of employee and non‑employee stock‑based compensation expense on selected statements of operations line items for the years ended December 31, 2016, 2015 and 2014. Year ended December 31, 2016 2015 2014 Employee Non-Employee Total Employee Non-Employee Total Employee Non-Employee Total (in thousands) Cost of revenues $ $ $ $ $ $ $ $ $ Research and development Selling, general and administrative Total $ $ $ $ $ $ $ $ As of December 31, 2016, approximately $19.4 million of unrecognized compensation expense, adjusted for estimated forfeitures, related to unvested awards will be recognized over a weighted‑average period of approximately 2.8 years. Valuation of Stock Option Grants to Employees The Company estimates the fair value of its stock options granted to employees on the grant date using the Black‑Scholes option‑pricing model. The fair value of employee stock options is amortized on a straight‑line basis over the requisite service period of the awards, generally the vesting period. The fair value of employee stock options was estimated using the following assumptions: Year ended December 31, 2016 2015 2014 Expected term — — 10.0 4.9 — 7.1 Expected volatility % — % % — 78.8 % 73.4 % — 87.0 % Expected dividend rate % 0 % 0 % Risk-free interest rate % — % % — 2.32 % 1.65 % — 2.04 % Expected Term : The expected term of options represents the period of time that options are expected to be outstanding. For granted "at-the-money" stock options, the Company estimated the expected term by using the simplified method up until December 31, 2015, which involved calculating the average of the time-to-vesting and the total contractual life of the options. Starting January 1, 2016, the Company uses a different approach by calculating the average of—(1) its employees’ historical stock options exercise behavior, and (2) the weighted-average of the time-to-vesting and the total contractual life of the options. For stock options that are not granted "at-the-money," the Company uses the binomial lattice model to calculate the expected term. Expected Volatility : The Company derived the expected volatility from the average historical volatilities of comparable publicly traded companies within its peer group over a period approximately equal to the expected term. Expected Dividend Rate : The Company has not paid and does not anticipate paying any dividends in the near future. Risk-Free Interest Rate : The risk-free interest rate assumption is based on U.S. Treasury yield in effect at the time of grant for zero coupon U. S. Treasury notes with maturities approximately equal to the expected term. Valuation of Stock Option Grants to Non-Employees Total options outstanding as of December 31, 2016, include 141,046 shares of option awards that were granted to non-employees, of which 10,456 shares are unvested. Stock-based compensation expense related to stock options granted to non-employees is recognized as the stock option is earned and the services are rendered. The Company believes that the estimated fair value of the stock options is more readily measurable than the fair value of the services rendered. The fair value of the stock options granted to non-employees is calculated at each reporting date using the Black-Scholes options-pricing model with the following assumptions: Year ended December 31, 2016 2015 2014 Expected term 2.7 — 3.2 — 9.8 4.4 — 10.0 Expected volatility 50.9 % — 72.6 % % — 75.4 % 71.9 % — 80.2 % Expected dividend rate 0 % 0 % 0 % Risk-free interest rate 0.68 % — 1.38 % % — 2.24 % 1.41 % — 2.61 %

Debt

Debt	12 Months Ended
	Dec. 31, 2016
Debt
Debt	8. Debt Senior Secured Term Loan In April 2013, as amended in June 2014, the Company entered into a senior secured term loan arrangement (the "Secured Loan Arrangement") with ROS Acquisition LP ("ROS"). The Secured Loan Arrangement provided for up to $40.0 million in borrowing capacity ("Credit Agreement"), a warrant to purchase shares of Common Stock, and an agreement to pay royalties on Company revenues ("Royalty Agreement"). The Company borrowed $20.0 million on the effective date of the Credit Agreement. The Credit Agreement provided for an interest rate equal to the greater of (a) LIBOR or (b) 1% per annum plus the applicable margin of 8% per annum or 9% floor on the outstanding balance of the term loan. The Royalty Agreement obligated the Company to make royalty payments of 1% applied to total Company fiscal year revenues of up to $50.0 million and 1.5% applied to fiscal year incremental revenues above $50.0 million. For the year ended December 31, 2015, the Company incurred approximately $1.4 million and $7.1 million in interest expenses under the Credit Agreement and royalty expenses under the Royalty Agreement, respectively. The $7.1 million in royalty expense included $1.8 million in royalty due and the remainder was for part of the $28.0 million pay-off to ROS. Please refer to paragraph below for pay-off details. For the year ended December 31, 2014, the Company incurred approximately $1.8 million and $2.2 million in interest expenses under the Credit Agreement and royalty expenses under the Royalty Agreement, respectively. The interest on the loan is set forth in the financial statements as interest expense below loss from operations. The effective yield was approximately 20.9% and 19.8%, respectively, for the year ended December 31, 2015 and 2014, excluding royalty and interest early termination payments. Under the terms of the Secured Loan Arrangement, the Company issued ROS a warrant to purchase 376,691 shares of common stock with an exercise price of $2.3229 per share. The Credit Agreement principal was due and payable on April 18, 2019. The Company could at its option, prepay the term loan borrowings subject to a prepayment premium equivalent to 10% of the outstanding principal. Prepayment of the amount due under the Credit Agreement did not eliminate the royalty payment obligation, which if not terminated, would have expired no later than April 18, 2023. In October 2015, the Company made a payment of $28.0 million to ROS to extinguish the amounts owed, which included the principal and royalty obligation. This terminated the term loan, royalty and all associated liens securing the Credit Agreement. Credit Line Agreement In September 2015, the Company entered into the Credit Line with UBS providing for a $50.0 million revolving line of credit which can be drawn down in increments at any time. In October 2015, the Company borrowed $32.0 million against the Credit Line, primarily to prepay all outstanding amounts under the Secured Loan Arrangement with ROS. The Credit Line bears interest at 30-day LIBOR plus 0.65%, and equals approximately 0.84% per annum at the time of the draw. In November, 2015, the Company borrowed an additional $10.0 million which bears interest at approximately 0.85% per annum. Interest of $0.1 million was accrued during the year ended December 31, 2015. In June 2016, the Company borrowed an additional $8.0 million from the Credit Line and repaid $1.0 million, thereby resulting in a remaining $0.4 million available for draw down, net of accrued interest of $0.6 million as of December 31, 2016. The outstanding balance of the Credit Line, including accrued interest, was $49.6 million as of December 31, 2016. 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. Equipment Financing Facility In April 2013, the Company entered into an equipment financing facility (the “Equipment Financing Facility”) with a financial institution pursuant to which the Company could borrow up to $5.0 million to fund equipment purchases. The financial institution maintained a security interest in the underlying equipment until payment in full of the loan. The loan bore interest at the financial institution's prime reference rate (defined as the 30-day LIBOR rate plus 2.50%) plus 4.10%, which equaled 7.35% upon closing of the agreement. In December 2014, the Company amended the Equipment Financing Facility increasing the loan amount to $5.9 million to fund equipment purchased. The Company paid interest on the unpaid principal at the financial institution's prime reference rate plus 3.10%, which equaled 6.35%. Under the terms of the Equipment Financing Facility, the loan would mature on May 31, 2017. Under the terms of the Equipment Financing Facility, the Company would be required to make 30 payments of principal and interest through the maturity of the loan in May 2017. In September 2015, the Company paid off the remaining principal balance of the equipment financing facility. The Company made a payment of $4.1 million, comprising of principal, interest and administrative fees settling all of its obligations under the loan.

Warrants

Warrants	12 Months Ended
	Dec. 31, 2016
Warrants.
Warrants	9. Warrants In 2007, the Company issued warrants to purchase an aggregate of 24,538 shares of common stock at an exercise price of $0.0978 per share to various holders. As of December 31, 2016, these warrants were fully exercised. In 2009, the Company granted warrants to purchase 33,742 shares of Series B convertible preferred stock at an exercise price of $1.8908 per share. The warrants were granted to a financial institution in connection with a secured equipment loan and expire on November 2, 2019. In connection with the IPO in July 2015, these warrants were converted into the right to purchase common stock at a one-to-one ratio. In December 2015, the financial institution net-exercised all 33,742 of their warrant shares at the strike price of $1.8908 per share. Based on the Company’s closing price of $11.57 per share on the prior business day, the Company issued 28,227 shares to the financial institution. In April 2014, the Company granted warrants to purchase approximately 376,691 warrants to purchase common stock at an exercise price of $2.3229 per common share. The warrants were granted to ROS Acquisition Offshore LP in connection with the Company’s senior secured term loan and expire on April 18, 2023. It was determined that the warrants granted are detachable and therefore are a stand-alone component of the senior secured term loan to be fair valued using Level III inputs as a separate derivative. As of December 31, 2016, these warrants remained exercisable for common stock. In connection with the Series F financing, the Series E preferred stockholders agreed to change the liquidation preference from two times to one times the liquidation value as described in the agreement. In exchange, on November 20, 2014, the Company issued common stock warrants to the Series E preferred stockholders to purchase 429,440 shares at $0.0163 per share. The warrants are carried in Additional Paid In Capital and the issuance of the warrants was treated as a deemed dividend by the common stockholder out of Additional Paid in Capital. In connection with the IPO in July 2015, such warrants were automatically net exercised into 429,042 shares of common stock.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2016
Convertible Preferred Stock.
Convertible Preferred Stock	10. Convertible Preferred Stock At the closing of the IPO in July 2015, 31,397,221 shares of outstanding convertible preferred stock were automatically converted into common stock on a one-to-one basis. Following the IPO, there were no shares of preferred stock outstanding. In connection with the IPO, the Company amended and restated its Amended and Restated Certificate of Incorporation to change the authorized capital stock to 750.0 million shares designated as common stock and 50.0 million shares designated as preferred stock, all with a par value of $0.0001 per share. As of December 31, 2014, the convertible preferred stock consisted of the following: Shares Shares Issued and Liquidation Proceeds, net of Series Authorized Outstanding Amount Issuance Costs (in thousands) A-1 $ $ A B C D E F $ $

CommonStock

CommonStock	12 Months Ended
	Dec. 31, 2016
Common Stock.
Common Stock	11. Common Stock The Company's Certificate of Incorporation, as restated in connection with the closing of the IPO, authorizes the Company to issue 750.0 million shares of common stock with a par value of $0.0001 per share. As of December 31, 2016 and December 31, 2015, the Company had 52.7 million and 50.3 million shares of common stock outstanding, respectively. Each shareholder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders. The Company's board of directors and stockholders approved an amendment to its Certificate of Incorporation to effect a 1-for-1.63 reverse split of its capital stock, which was effected on June 19, 2015. All references to common stock, options to purchase common stock, restricted stock, share data, per share data, warrants, convertible preferred stock and related information have been retroactively adjusted where applicable in this report to reflect the reverse stock split of the Company's capital stock as if it had occurred at the beginning of the earliest period presented.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Taxes
Income Taxes	12. Income Taxes The Company's effective tax rates for the years ended December 31, 2016 and 2015 differ from the U.S. federal statutory rate as follows: December 31, 2016 2015 (in thousands, except percentages) U.S. federal taxes (benefit) at statutory rate $ % $ % State tax expense % % Research and development credits % % Stock-based compensation % % Mark to market fair value adjustments % % Other nondeductible items % % Change in valuation allowance % % Provision for income taxes $ % $ — — % Due to its history of operating losses, the Company has not recorded any income tax expense for the year ended December 31, 2016, with the exception of $142,000 of foreign withholding tax in 2016. As the provision for income taxes was not significant for and the year ended December 31, 2015, any income taxes were reclassified in other income and expenses. Deferred income taxes reflect the net tax effects of temporary differences between carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes as well as net operating loss and tax credit carryforwards. The components of the net deferred income tax assets are as follows: December 31, 2016 2015 (in thousands) Deferred tax assets Net operating loss carryforwards $ $ Research and development tax credit carryforwards Reserves and accruals Stock-based compensation Total deferred tax assets before valuation allowance Less: valuation allowance Deferred tax liabilities Property and equipment Net deferred tax assets $ — $ — The Company established a full valuation allowance against its net deferred tax assets in 2016 and 2015 due to the uncertainty surrounding realization of these assets. The valuation allowance increased by $34.5 million, $24.5 million and $0.9 million during the years ended December 31, 2016, 2015 and 2014, respectively. As of December 31, 2016, the Company had federal and state net operating loss (“NOLs”) carryforwards of approximately $205.3 million and $109.6 million, respectively, which begin to expire in 2027 and 2017, respectively, if not utilized. The deferred tax assets related to NOLs do not include excess tax benefits from employee stock option exercises. Equity will be increased by $7.2 million, if and when such deferred tax assets are ultimately realized. The Company uses ASC 740 ordering when determining when excess tax benefits have been realized. The Company also had federal research and development credit carryforwards of approximately $8.5 million, which begin to expire in 2027, and state research and development credit carryforwards of approximately $5.8 million, which can be carried forward indefinitely. Realization of these deferred tax assets would require $226.2 million in taxable income to fully utilize. Realization is dependent on generating sufficient taxable income prior to expiration of the loss and credit carryforwards. Federal and California tax laws impose substantial restrictions on the utilization of NOLs and credit carryforwards in the event of an "ownership change" for tax purpose, as defined in Section 382 of the Internal Revenue Code. Accordingly, the Company's ability to utilize these carryforwards may be limited as the result of such ownership change. Such a limitation could result in limitation in the use of the NOLs in future years and possibly a reduction of the NOLs available. A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows: December 31, 2016 2015 (in thousands) Balance at beginning of year $ $ Additions based on tax positions related to the current year Additions for tax positions of prior years — Balance at end of year $ $ The Company adopted the provisions of ASC 740-10-50, Accounting for Uncertainty in Income Taxes , on January 1, 2009. During the years ended December 31, 2016 and 2015, the amount of unrecognized tax benefits increased $1.9 million and $1.0 million, respectively, due to additional research and development credits generated during the year. As of December 31, 2016 and 2015, the total amount of unrecognized tax benefits was $4.3 million and $2.4 million, respectively. The reversal of the uncertain tax benefits would not affect the Company's effective tax rate to the extent that it continues to maintain a full valuation allowance against its deferred tax assets. The Company is subject to U.S. federal income taxes and to income taxes in various states in the United States. Tax regulations within each jurisdiction are subject to the interpretation of the related tax laws and regulations, and require significant judgment to apply. The Company is subject to U.S. federal, state and local tax examinations by tax authorities for all prior tax years since incorporation. The Company does not anticipate significant changes to its current uncertain tax positions through December 31, 2017. The Company recognizes any interest and/or penalties related to income tax matters as a component of income tax expense. As of December 31, 2016, there were no accrued interest and penalties related to uncertain tax positions.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2016
Related-Party Transactions
Related-Party Transactions	13. Related‑Party Transactions The Company entered into a full recourse promissory note with the Company’s chief executive officer, in April 2012 whereby the Company loaned Dr. Rabinowitz $154,000. This interest only loan bore interest at a rate per annum of 1.15%, compounded annually. This loan, including all accrued interest, was repaid in full by Dr. Rabinowitz in May 2015. The Company entered into a full recourse promissory note with Jonathan Sheena, the Company’s chief technology officer, in April 2012 whereby the Company loaned Mr. Sheena $38,280. This interest only loan bore interest at a rate per annum of 1.15%, compounded annually. This loan, including all accrued interest, was repaid in full by Mr. Sheena in May 2015.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2016
Net Loss per Share
Net Loss per Share	14. Net Loss per Share Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period. Prior to the Company’s IPO of its common stock, the Company’s convertible preferred stock was entitled to receive dividends, prior and in preference to any declaration or payment of any dividend on common stock and thereafter participate pro rata on an as converted basis with the common stock holders on any distributions to common stockholders. The convertible preferred shares were therefore considered to be participating securities. As a result, the Company calculated the net loss per share using the two-class method. Accordingly, the net loss attributable to common stockholders is derived from the net loss for the period and, in periods in which the Company has net income attributable to common stockholders, an adjustment is made for the noncumulative dividends and allocations of earnings to participating securities based on their outstanding shareholder rights. Under the two-class method, the net loss attributable to common stockholders is not allocated to the convertible preferred stock as the convertible preferred stock did not have a contractual obligation to share in the Company’s losses. The diluted net income per share attributable to common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. In periods when the Company has incurred a net loss, convertible preferred stock, options to purchase common stock, common stock warrants and common stock subject to repurchase are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is antidilutive. The following table provides the basic and diluted net loss per common share computations for the years ended December 31, 2016, 2015 and 2014. Year ended December 31, (in thousands, except per share data) 2016 2015 2014 Basic and diluted loss per share: Net loss $ $ $ Weighted-average common shares outstanding Less: weighted-average unvested common shares subject to repurchase Weighted-average number of shares used in computing net loss per share, basic and diluted Basic and diluted net loss per share $ $ $ Potentially dilutive shares that were not included in the diluted per share calculations because they would be antidilutive as of the years ended December 31, 2016, 2015 and 2014 were as follows: Year ended December 31, 2016 2015 2014 Options to purchase common stock Warrants to purchase common stock Restricted stock units — — Employee stock purchase plan — — Common stock subject to repurchase — Convertible preferred stock — —

Geographic Information

Geographic Information	12 Months Ended
	Dec. 31, 2016
Geographic Information
Geographic Information	15. Geographic Information The following table presents total revenues by geographic area based on the location of the Company’s customers: Year ended December 31, (in thousands) 2016 2015 2014 United States $ $ $ Americas, excluding U.S. Europe, Middle East, India, Africa Other Total $ $ $

Quarterly Financial Data

Quarterly Financial Data	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Data
Quarterly Financial Data	16 . Quarterly Financial Data (unaudited) Three months ended December 31, September 30, June 30, March 31, (in thousands, except per share data) 2016 Operating results: Total revenues $ $ $ $ Cost of product, licensing and other revenues Gross profit Other costs and expenses Interest expense and other (expense) income, net Income tax expense — — Net loss Per share data: Net loss - basic and diluted $ $ $ $ 2015 Operating results: Total revenues $ $ $ $ Cost of product, licensing and other revenues Gross profit Other costs and expenses Interest expense and other (expense) income, net Net loss Per share data: Net loss - basic and diluted $ $ $ $

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2016
Subsequent Events
Subsequent Events	17 . Subsequent Events In January 2017, the Company amended an existing agreement with one of its vendors to revise its minimum purchase commitments of gene sequencing tests in exchange for certain additional rights under the agreement. The revised minimum purchase commitments amount to $3.6 million for 2017. For 2018, the minimum purchase commitments total $4.5 million. If the Company fails to meet its minimum purchase commitments in 2018, there is no financial consequence, but it would lose certain exclusivity rights under the agreement.

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”).
Need to Raise Additional Capital	Need to Raise Additional Capital The Company has incurred net losses since its inception and anticipates net losses and negative operating cash flows for the near future. For the year ended December 31, 2016, the Company had a net loss of $95.8 million, and as of December 31, 2016, it had an accumulated deficit of $345.9 million. At December 31, 2016, the Company had $15.3 million in cash and cash equivalents, $130.9 million in marketable securities, and $49.6 million of outstanding debt with accrued interest. While the Company has introduced multiple products that are generating revenues, these revenues have not been sufficient to fund all operations. Accordingly, the Company has funded the portion of operating costs that exceeds revenues through a combination of equity issuances, debt issuances, and other financings. The Company expects 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 would 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 require 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, commercialization and marking of its products and significantly scale back its business and operations. Based on our current business plan, we believe that our existing cash and marketable securities will be sufficient to meet our anticipated cash requirements for at least 12 months after March 16, 2017.
Principles of Consolidation	Principles of Consolidation The accompanying condensed consolidated financial statements include all the accounts of the Company and its subsidiary. The Company established a subsidiary that operates in the state of Texas in December 2014 to support the Company’s laboratory and operational functions, which became active in the second quarter of 2015. All intercompany balances and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with U.S. GAAP 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, accrued liability for potential refund requests, stock-based compensation, the fair value of common stock and fair value of debt accounted for under ASC 815, as well as income tax uncertainties. 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; however, actual results could differ from these estimates and could have an adverse effect on the Company's financial statements.
Fair Value	Fair Value The Company discloses the fair value of financial instruments for financial assets and liabilities for which the value is practicable to estimate. Fair value is defined as the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The Company carried senior secured term loan and warrants at fair value according to the fair value measurement guidance.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash and money market deposits with financial institutions.
Restricted Cash	Restricted Cash The Company discloses both short-term and long-term restricted cash. Short-term restricted cash consists of $1.1 million, which secured a $0.8 million letter of credit for the sublease of the First Space (defined in Note 6) that expired in October 2016, however, the associated restriction has not been released as of December 31, 2016, and a $0.3 million letter of credit for the sublease of the Second Space (defined in Note 6), which expired in January 2017. Long-term restricted cash consists of $0.3 million deposit per credit card terms.
Investments	Investments Management determines the appropriate classification of securities at the time of purchase and reevaluates 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, even though the stated maturity may be more than one year from the current balance sheet date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive loss, which is a separate component of stockholders’ equity.
Risk and Uncertainties	Risk and Uncertainties 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 bills third-party payers for certain tests performed. The amount that is ultimately received from the payer for the Company’s claim and the timing of such payments are subject to the determination of the payer based on the nature of the test performed and their view of the Company’s business practices with respect to collections of plan deductibles and co-payments from patients and other activities. This determination can impact both the amount and timing of when the Company’s invoices are collected. Payers may also withhold payments and request refunds of prior payments if the Company does not perform in accordance with the policies of these payers. The Company performs evaluations of financial conditions for clinics and laboratory partners and generally does not require collateral to support credit sales. For 2016, 2015 and 2014, there were no customers exceeding 10% in total revenue. As of December 31, 2016, one customer had an outstanding balance of approximately 52% of net accounts receivable, and as of December 31, 2015, no customers had an outstanding balance greater than 10% of net accounts receivable.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts Trade accounts receivable are recorded at the amount billed to the laboratory partners and clinics. Reducing this amount is an allowance for doubtful accounts for estimated losses resulting from the inability of its customers to make the contracted payments. Management analyzes accounts receivable and historical bad debt experience, customer creditworthiness, current economic trends, and changes in customer payment history when evaluating the adequacy of the allowance for doubtful accounts. Accounts receivable are written off against the allowance when there is substantive evidence that the account will not be paid.
Revenue Recognition	Revenue Recognition The Company generally bills an insurance carrier, a clinic or a patient for the test upon delivery of the test result. The Company also bills patients directly for out-of-pocket costs not covered by their insurance carriers representing co-pays and deductibles in accordance with their insurance carrier and health plans. For tests performed, where an agreed upon reimbursement rate or fixed fee and a predictable history or likelihood of collections exists, the Company recognizes revenues upon delivery of the test report to the prescribing physician based on the established billing rate less contractual and other adjustments, such as an allowance for doubtful accounts, to arrive at the amount that the Company expects to collect. In all other situations, as the Company does not have sufficient history of collection and is not able to determine collectability, the Company recognizes revenues when cash is received. The Company may not get reimbursed for tests completed if the tests are not covered under the insurance carrier’s reimbursement policies or the Company is not a qualified provider to the insurance carrier. From time to time, the Company receives requests for refunds of payments previously made by insurance carriers. The Company has established an accrued liability for potential refund requests based on its experience, which is accounted for as reductions in revenues in the statement of operations and comprehensive loss. In cases where the Company sells its tests through its laboratory partners, the majority of the laboratory partners bill the patient, clinic, or insurance carrier for the performance of the Company's tests. For tests sold through a limited number of its laboratory partners, the Company bills directly to a patient, clinic or insurance carrier, or a combination of the insurance carrier and patient for the fees. The Company considers its services rendered when it delivers reports of its test results to the laboratory partner, clinic or patient. When the Company has contracted fixed rates for its services and collectability of its revenues is reasonably assured, it recognizes revenues upon delivery of test reports. The fixed fees identified in contracts with laboratory partners change only if a pricing amendment is agreed upon between both parties. For cases in which there is no fixed price established with a laboratory partner, the Company then recognizes revenues from partner distributed tests on a cash basis. Certain of the Company's arrangements include multiple deliverables. For revenue arrangements with multiple deliverables, the Company evaluates each deliverable to determine whether it qualifies as a separate unit of accounting. This determination is based on whether the deliverable has "stand-alone value" to the customer and whether a general right of return exists. The consideration that is fixed or determinable is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. The consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. The Company uses judgment in identifying the deliverables in its arrangements, assessing whether each deliverable is a separate unit of accounting, and in determining the best estimate of selling price for certain deliverables. The Company also uses judgment in determining the period over which the deliverables are recognized in certain of its arrangements. Any amounts received that do not meet the criteria for revenue recognition are recorded as deferred revenue until such criteria are met. The Company receives royalty revenue through the licensing and the provisioning of services to support the use of the Company's proprietary technology with its customer. Royalty revenues are recognized when earned under the terms of the related agreements and are included in licensing and other revenues in the statements of operations and comprehensive loss. The Company recognizes revenue from the cloud-based distribution service offering. The Company grants its customers licenses to use the Company’s proprietary intellectual properties and the cloud-based Natera software, and provides the other services to support the use of the Company's proprietary technology with its customers. Natera’s proprietary software is used in connection with the analysis of DNA sequence data in a manner yielding a result indicating the likely presence or absence of full or partial chromosomal abnormalities. The licensees do not have the right to possess Natera software, but rather are treated as software as a service. The revenues are recognized on an accrual basis (assuming all revenue recognition criteria are met) under the terms of the related agreements and are included in licensing and other revenues in the statements of operation and comprehensive loss.
Cost of Product, Licensing and Other Revenues	Cost of Product, Licensing and Other Revenues Cost of product, licensing and other revenues includes the cost of materials, direct labor of laboratory personnel, equipment and infrastructure expenses associated with processing blood and other samples, quality control analyses, and shipping charges to transport samples and specimens from ordering physicians, clinics or individuals. Infrastructure expenses include allocated facility and related occupancy costs. Costs associated with the performance of diagnostic services are recorded as tests are processed.
Research and Development	Research and Development The Company records research and development costs in the period incurred. Research and development costs consist of personnel costs, contract services, cost of materials utilized in performing tests, costs of clinical trials and allocated facilities and related overhead expenses.
Advertising Costs	Advertising Costs The Company expenses advertising costs as incurred. The Company incurred advertising costs of $0.4 million, $1.1 million and $1.1 million for the years ended December 31, 2016, 2015 and 2014, respectively.
Product Shipment Costs	Product Shipment Costs The Company expenses product shipment costs in cost of product, licensing and other revenues in the accompanying statements of operations. Shipping and handling costs for the years ended December 31, 2016, 2015 and 2014 were $8.2 million, $7.0 million and $4.5 million, respectively.
Income Taxes	Income Taxes Income taxes are recorded in accordance with Financial Accounting Standards Board ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Tax benefits are recognized when it is more likely than not that a tax position will be sustained during an audit. Deferred tax assets are reduced by a valuation allowance if current evidence indicates that it is considered more likely than not that these benefits will not be realized.
Stock-Based Compensation	Stock‑Based Compensation Stock‑based compensation related to stock options and restricted stock units (“RSUs”) granted to the Company’s employees 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. No compensation cost is recognized on stock options for employees who do not render the requisite service and therefore forfeit their rights to the stock options. The Company uses the Black‑Scholes option‑pricing model to estimate the fair value of its stock options. The Company accounts for stock options issued to non-employees based on the estimated fair value of the awards using the Black-Scholes option-pricing model. The measurement of stock-based compensation is subject to periodic adjustments as the underlying equity instruments vest, and the resulting change in value, if any, is recognized in the Company's statements of operations and comprehensive loss during the period that the related services are rendered. The Black-Scholes option-pricing model requires the input of the Company's expected stock price volatility, the expected term of the awards, a risk-free interest rate, and expected dividends. Determining these assumptions requires significant judgment. The expected term was based on the simplified method and where the Company did not qualify to use the simplified method, the Company used the lattice model, and the volatility rate was based on that of publicly traded companies in the DNA sequencing, diagnostics, or personalized medicine industries. When selecting the public companies in these industries to be used in the volatility calculation, companies were selected with comparable characteristics to the Company, including enterprise value and financial leverage. Companies were also selected with historical share price volatility sufficient to meet the expected term of the Company's stock options. The historical volatility data was computed using the daily closing prices for the selected companies' shares during the equivalent period of the calculated expected term of the Company's stock options. The expected term of the non-employee option grants was based on their remaining contractual life at the measurement date. The risk-free interest rate assumption was based on U.S. Treasury instruments with maturities that were consistent with the option's expected term. The expected dividend assumption was based on the Company's history and expectation of dividend payouts. Starting January 1, 2016, the Company uses a different approach to estimate the expected term of its stock option awards, which involves calculating the average of—(1) its employees’ historical stock option exercise behavior, and (2) the weighted-average of the time-to-vesting and the total contractual life of the options. The Company applied this change in methodology prospectively and accounted for it as a change in accounting estimate.
Warrants	Warrants The Company accounts for warrants to purchase shares of its common stock as a liability at fair value on the balance sheet date because the Company may be obligated to redeem these warrants at some point in the future. The warrants are subject to remeasurement at each balance sheet date, with changes in fair value recognized as a gain or loss from the changes in fair value of the warrants in the statements of operations. The Company will continue to adjust the liability for changes in fair value until such time that the warrants are converted or expire.
Capitalized Software Held for Internal Use	Capitalized Software Held for Internal Use The Company capitalizes costs of software held for internal use during the application development stage of a project and amortize those costs over their estimated useful lives of three years. The net book value of capitalized software held for internal use was $1.3 million and $0.8 million as of December 31, 2016 and 2015, respectively. Amortized expense for amounts previously capitalized for the years ended December 31, 2016 and 2015 was $0.6 million and $0.2 million, respectively. There was no amortization of such capitalized costs for the year ended December 31, 2014.
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive 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. As of December 31, 2016, and 2015, accumulated other comprehensive loss consisted of $0.7 million and $1.4 million of unrealized losses on available-for-sale marketable securities. There was $0.2 million reclassified out of accumulated other comprehensive loss during the year ended December 31, 2016, and no reclassifications were made in the years ended December 31, 2015 and 2014.
Property and Equipment	Property and Equipment Property and equipment, including purchased and internally developed software, are stated at cost. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, which are generally three years. Leasehold improvements are amortized using the straight-line method over the estimated useful lives of the assets or the remaining term of the lease, whichever is shorter. The Company periodically reviews the depreciable lives assigned to property and equipment placed in service and change the estimates of useful lives to reflect the results of such reviews. During the third and fourth quarters of 2016, the Company performed an assessment on its estimated use of certain sequencing and automation equipment. As a result of the assessment, it was determined that the service lives of several of such equipment over which the remaining economic benefit was to be received from were significantly shorter than initially expected by the Company. Additionally, the Company wrote off the remaining maintenance service contract associated with the equipment described above. The Company accounted for the revision of its depreciation estimates on the sequencing and automation equipment and the write off of the unamortized prepaid maintenance as a change in accounting estimate, which increased its loss from operations and net loss by $1.7 million, and increased its basic and diluted net loss per share by $0.04 for the year ended December 31, 2016. During the second quarter of 2015, the Company increased the depreciable lives of certain sequencing and automation equipment from three years to five years. The effect of this change in estimate for the year ended December 31, 2015 was a decrease in loss from operations and net loss of $1.7 million, and a decrease in basic and diluted net loss per share of $0.07.
Impairment of Long-lived Assets	Impairment of Long-lived Assets The Company evaluates its long-lived assets for indicators of possible impairment when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. The Company then compares the carrying amounts of the assets with the future net undiscounted cash flows expected to be generated by such asset. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s fair value determined using discounted estimates of future cash flows. For the years ended December 31, 2016 and 2015, we recorded asset impairment losses of $2.1 million and $1.6 million, respectively. See Note 5 for more detail about the asset impairment.
Inventory	Inventory Inventory is valued at the lower of the standard cost, which approximates actual cost, or market. Cost is determined using the first-in, first-out ("FIFO") method. Inventory consists entirely of supplies, which are consumed when providing its test reports, and therefore does not maintain any finished goods inventory. The Company enters into inventory purchases and commitments so that it can meet future delivery schedules based on forecasted demand for its tests. In December 2016, the Company determined $2.1 million of inventory as obsolete in connection with its impairment analysis of the associated automation and sequencing equipment described above, and recorded an associated charge for these materials.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or FASB 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 recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In August 2014, FASB issued Accounting Standards Update No. 2014‑15 (“ASU 2014-15”), Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern . ASU 2014‑15 requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. ASU 2014‑15 is effective for the Company in the first quarter of 2017 with early adoption permitted. The Company has elected to early adopt this guidance for its annual reporting period ending December 31, 2016, and this ASU applies to all future annual and interim reporting periods. Upon adoption, the Company is required to perform assessment using detailed prospective financial information during each interim period and annually to determine whether substantial doubt exists about its ability to continue as a going concern for at least 12 months from the issuance date of the financial statements, and to provide the related disclosures. As a result of the analysis, the adoption of ASU 2014‑15 did not have a material impact on the Company’s financial statements and related disclosures, although the related disclosures could be impacted in future periods. In May 2014, FASB issued Accounting Standards Update No. 2014-09 (“ASU 2014-09”), Revenue from Contracts with Customers to provide guidance on revenue recognition. To date, the Company’s revenues have been derived primarily from contracts with insurance carriers, patients, clinics and licensing arrangements. Approximately 82% of the Company’s revenues are recognized on the cash basis, and based on the Company’s preliminary assessment, this portion of revenues may be recognized at an earlier date than in the period of actual cash receipt. Consideration is received from either patients, clinics, or insurance carriers and/or any combination of the three, and licensees. Each one of these arrangements, whether sell-in or sell-through, is considered unique and being evaluated individually under the five-step process prescribed by the new revenue standard. Currently, the Company continues to assess its contracts with insurance carriers. The Company has not completed its analysis, and it is evaluating whether the impact of adopting ASU 2014-09 will be material to its financial statements. ASU 2014-09 will be effective for the Company in the first quarter of 2018, with early adoption permitted starting the first quarter of 2017. Upon adoption, ASU 2014-09 can be applied retrospectively to all periods presented or using the modified retrospective approach, which requires the cumulative effect of changes reflected in the opening balance of retained earnings only in the most current period presented. The Company has not yet determined which method will be used upon adoption, and will plan on adopting the new guidance in the first quarter of 2018. In July 2015, FASB issued Accounting Standards Update No. 2015-11 (“ASU 2015-11”), Inventory (Topic 330): Simplifying the Measurement of Inventory (ASU 2015-11). ASU 2015-11 simplifies the subsequent measurement of inventory by replacing today’s lower of cost or market test with a lower of cost and net realizable value test. ASU 2015-11 is effective for the Company in the fiscal year beginning after December 15, 2016, and interim periods within those fiscal years. The Company does not expect the adoption of ASU 2015‑11 will have a material impact on its financial statements. In November 2015, FASB issued Accounting Standards Update No. 2015-17 (“ASU 2015-17”), Balance Sheet Classification of Deferred Taxes , which simplifies the presentation of deferred taxes by requiring that deferred tax assets and liabilities be presented as noncurrent on the balance sheet. ASU 2015-17 is effective for the Company in the fiscal year beginning after December 15, 2016, and interim periods within those fiscal years. The Company currently does not have any deferred tax assets or liabilities on its balance sheet as a full valuation allowance has been reserved against them, and it does not expect the adoption of ASU 2015-17 will have a material impact on its financial statements. In February 2016, the FASB issued Accounting Standards Update No. 2016-02 (“ASU No. 2016-02”), Leases . ASU 2016-02 is aimed at making leasing activities more transparent and comparable, and requires substantially all leases be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. ASU 2016-02 is effective for the Company in the fiscal year beginning after December 15, 2018, and interim periods within those fiscal years with early adoption permitted. The Company plans to adopt this new guidance prospectively in the first quarter of 2019. The Company is evaluating the impact of the adoption of this guidance on its financial statements, and expects that it will increase our lease assets and correspondingly increase our lease liabilities. In March 2016, the FASB issued Accounting Standards Update No. 2016-09 (“ASU 2016-09”), Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. ASU 2016-09 includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. The new guidance requires any excess tax benefits (“windfalls”) and tax deficiencies (“shortfalls”) associated with vested or settled share-based awards to be recognized in the income statement rather than additional paid-in capital, which is to be applied prospectively. Further, windfalls will be required to be presented as an operating activity rather than as an outflow from operating activity and an inflow to financing activity, as required by the existing guidance. This new presentation guidance can be applied retrospectively or prospectively. The new guidance also eliminates the requirement to delay the recognition of windfalls until it begins to reduce current income taxes payable, and this is to be applied using the modified retrospective approach, with a cumulative effect adjustment to opening retained earnings. In addition, ASU 2016-09 allows entities to withhold an amount up to the employees’ maximum individual tax rate in the relevant jurisdiction without having to account for the award as a liability-based award, and this guidance is to be applied using the modified retrospective approach, with a cumulative effect adjustment to opening retained earnings. ASU 2016-09 also permits forfeitures to be either estimated, as required by the existing guidance, or recognized when they occur. The change in the accounting for forfeitures is required to be applied using a modified retrospective approach, with a cumulative effect adjustment to opening retained earnings. The new guidance will be effective for public entities in fiscal years beginning after December 15, 2016. The Company plans to adopt this new guidance in the first quarter of 2017 and does not expect a material impact on its financial statements given the full valuation allowance position on its deferred tax assets. In August 2016, the FASB issued Accounting Standards Update No. 2016-15 (“ASU 2016-15”), Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (A Consensus of the Emerging Issues Task Force). The purpose of ASU 2016-15 is to limit diversity in the classification of certain transactions in the statement of cash flows. Such transactions include (1) debt prepayment or debt extinguishment costs, (2) settlement of zero-coupon bonds, (3) contingent consideration payments made after a business combination, (4) proceeds from insurance claims settlement, (5) proceeds from settlement of life insurance policies, and (6) distributions of equity method investments. ASU 2016-15 will be effective for the Company in the fiscal year beginning after December 15, 2017, and interim periods within that fiscal year. The Company is currently evaluating the impact of adopting ASU 2016-15 on its financial statements. In November 2016, the FASB issued Accounting Standards Update No. 2016-18 (“ASU 2016-18”), Statement of Cash Flows (Topic 230): Restricted Cash. The purpose of ASU 2016-18 is to eliminate the diversity in classifying and presenting changes in restricted cash in the statements of cash flows. The new guidance requires restricted cash to be combined with cash and cash equivalents when reconciling the beginning and ending balances of cash on the statement of cash flows, thereby no longer requiring transactions such as transfers between restricted and unrestricted cash to be treated as a cash flow activity. Further, the new guidance requires the nature of the restrictions to be disclosed, as well as a reconciliation between the balance sheet and the statement of cash flows on how restricted and unrestricted cash are segregated. The new guidance will be effective for the Company in the fiscal year beginning after December 15, 2017, and interim periods within that fiscal year, with early adoption permitted. The Company is currently evaluating the effect the new guidance is expected to have on its financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Summary of financial assets and liabilities measured on recurring basis	December 31, 2016 December 31, 2015 Level I Level II Level III Total Level I Level II Level III Total (in thousands) Financial Assets: Money market deposits $ $ — $ — $ $ $ — $ — $ U.S. Treasury securities — — — — U.S. agency securities — — — — Municipal securities — — — — Total financial assets $ $ $ — $ $ $ $ — $ Current Liabilities: Warrants $ $ — $ $ $ — $ — $ $ Total financial liabilities $ — $ — $ $ $ — $ — $ $
Summary of quantitative information about inputs and valuation methodologies	Weighted Average Interest on Fair Value at Significant Discount Rate December 31, 2016 Valuation Methodology Unobservable Input (range, if applicable) (in thousands) Warrants $ Black-Scholes Option Pricing Model Volatility %
Warrants
Rollforward of fair value determined by Level 3 inputs	Warrants 2016 2015 (in thousands) Beginning balance $ $ Warrants exercised — Change in fair value Ending balance $ $
Long-term Debt
Rollforward of fair value determined by Level 3 inputs	Term Loan 2016 2015 (in thousands) Beginning balance $ — $ Change in fair value recognized in non-operating expense — Loan payment — Ending balance $ — $ —

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Financial Instruments
Schedule of available-for-sale securities	December 31, 2016 December 31, 2015 Amortized Gross Gross Estimated Fair Amortized Gross Gross Estimated Fair (in thousands) Money market deposits $ $ — $ — $ $ $ — $ — $ U.S. Treasury securities — U.S. agency securities — — Municipal securities — Total $ $ — $ $ $ $ $ $ Classified as: Cash equivalents $ $ Short-term investments Total $ $
Summarized portfolio of available-for-sale securities by contractual maturity	December 31, 2016 Amortized Fair (in thousands) Less than one year $ $ Greater than one year but less than five years Total $ $

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2016
Balance Sheet Components
Schedule of allowance for doubtful accounts	December 31, December 31, 2016 2015 (in thousands) Beginning balance $ $ Provision for estimated bad debts Write offs Ending balance $ $
Schedule of property and equipment	December 31, December 31, Useful Life 2016 2015 (in thousands) Machinery and equipment 3-5 years $ $ Furniture and fixtures 3 years Computer equipment 3 years Capitalized software held for internal use 3 years Leasehold improvements Life of lease Construction-in-process Less: Accumulated depreciation and amortization Total Property and equipment, net $ $
Schedule of accrued compensation	December 31, December 31, 2016 2015 (in thousands) Accrued paid time off $ $ Accrued commissions Accrued bonuses Other accrued compensation Total accrued compensation $ $
Schedule of other accrued liabilities	December 31, December 31, 2016 2015 (in thousands) Overpayments from insurance carriers $ $ Other accrued expenses Testing and laboratory materials from suppliers Marketing and corporate affairs Leasehold improvement projects in progress — Accrued specimen service fees Accrued shipping charges Sales tax payable Clinical trials and studies Accrued rent Legal, audit and consulting fees Deferred lease obligation — Total other accrued liabilities $ $

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies
Schedule of future minimum lease payments	Operating Leases (in thousands) Year ending December 31: 2017 $ 2018 2019 2020 2021 2022 and thereafter Total future minimum lease payments $

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of stock option activity	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, 2015 $ 8.31 $ Additional shares authorized — Options granted $ Options exercised — $ Options forfeited $ Balance at December 31, 2016 $ 7.55 $ Exercisable at December 31, 2016 $ 6.51 $ Vested and expected to vest at December 31, 2016 $ 7.55 $
Restricted stock units	Weighted-Average Grant Date Shares Fair Value Balance at December 31, 2015 — $ — Granted $ Vested $ Canceled/forfeited $ Balance at December 31, 2016 $
Summary of stock-based compensation expenses	Year ended December 31, 2016 2015 2014 Employee Non-Employee Total Employee Non-Employee Total Employee Non-Employee Total (in thousands) Cost of revenues $ $ $ $ $ $ $ $ $ Research and development Selling, general and administrative Total $ $ $ $ $ $ $ $
Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of assumptions used in valuation of fair value of employee stock options	Year ended December 31, 2016 2015 2014 Expected term — — 10.0 4.9 — 7.1 Expected volatility % — % % — 78.8 % 73.4 % — 87.0 % Expected dividend rate % 0 % 0 % Risk-free interest rate % — % % — 2.32 % 1.65 % — 2.04 %
Non-employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of assumptions used in valuation of fair value of employee stock options	Year ended December 31, 2016 2015 2014 Expected term 2.7 — 3.2 — 9.8 4.4 — 10.0 Expected volatility 50.9 % — 72.6 % % — 75.4 % 71.9 % — 80.2 % Expected dividend rate 0 % 0 % 0 % Risk-free interest rate 0.68 % — 1.38 % % — 2.24 % 1.41 % — 2.61 %

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2016
Convertible Preferred Stock.
Schedule of convertible preferred stock	Shares Shares Issued and Liquidation Proceeds, net of Series Authorized Outstanding Amount Issuance Costs (in thousands) A-1 $ $ A B C D E F $ $

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Taxes
Schedule of effective tax rates differing from U.S. federal statutory rate	December 31, 2016 2015 (in thousands, except percentages) U.S. federal taxes (benefit) at statutory rate $ % $ % State tax expense % % Research and development credits % % Stock-based compensation % % Mark to market fair value adjustments % % Other nondeductible items % % Change in valuation allowance % % Provision for income taxes $ % $ — — %
Schedule of tax effects of temporary differences that give rise to significant portions of the deferred tax assets	December 31, 2016 2015 (in thousands) Deferred tax assets Net operating loss carryforwards $ $ Research and development tax credit carryforwards Reserves and accruals Stock-based compensation Total deferred tax assets before valuation allowance Less: valuation allowance Deferred tax liabilities Property and equipment Net deferred tax assets $ — $ —
Schedule of reconciliation of the beginning and ending amount of gross unrecognized tax benefits	December 31, 2016 2015 (in thousands) Balance at beginning of year $ $ Additions based on tax positions related to the current year Additions for tax positions of prior years — Balance at end of year $ $

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Net Loss per Share
Basic and diluted net loss per common share	Year ended December 31, (in thousands, except per share data) 2016 2015 2014 Basic and diluted loss per share: Net loss $ $ $ Weighted-average common shares outstanding Less: weighted-average unvested common shares subject to repurchase Weighted-average number of shares used in computing net loss per share, basic and diluted Basic and diluted net loss per share $ $ $
Potentially dilutive shares not included in the calculation of dilutive EPS	Year ended December 31, 2016 2015 2014 Options to purchase common stock Warrants to purchase common stock Restricted stock units — — Employee stock purchase plan — — Common stock subject to repurchase — Convertible preferred stock — —

Geographic Information (Tables)

Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2016
Geographic Information
Schedule of total revenue by geographic area	Year ended December 31, (in thousands) 2016 2015 2014 United States $ $ $ Americas, excluding U.S. Europe, Middle East, India, Africa Other Total $ $ $

Quarterly Financial Data (Table

Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Data
Schedule of quarterly financial data	Three months ended December 31, September 30, June 30, March 31, (in thousands, except per share data) 2016 Operating results: Total revenues $ $ $ $ Cost of product, licensing and other revenues Gross profit Other costs and expenses Interest expense and other (expense) income, net Income tax expense — — Net loss Per share data: Net loss - basic and diluted $ $ $ $ 2015 Operating results: Total revenues $ $ $ $ Cost of product, licensing and other revenues Gross profit Other costs and expenses Interest expense and other (expense) income, net Net loss Per share data: Net loss - basic and diluted $ $ $ $

Description of Business (Detail

Description of Business (Details) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2016segment	Dec. 31, 2015$ / sharesshares
Number of operating segments | segment		1
Common stock
Initial public offering (in shares) | shares			10,900,000
Initial public offering price (in dollars per share) | $ / shares			$ 11.57
IPO | Common stock
Initial public offering (in shares) | shares	10,900,000
Initial public offering price (in dollars per share) | $ / shares	$ 18
Proceeds from initial public offering, net of offering costs | $	$ 178.5

Summary of Significant Accoun38

Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Jan. 31, 2013
Policies
Net (loss) income	$ (37,907)	$ (26,017)	$ (23,156)	$ (8,685)	$ (22,960)	$ (17,630)	$ (19,681)	$ (10,004)	$ (95,765)	$ (70,275)	$ (5,152)
Accumulated deficit	345,848				250,083				345,848	250,083
Cash and cash equivalents	15,256				28,947				15,256	28,947	$ 87,176		$ 30,496
Short-term investments	130,860				201,586				130,860	201,586
Outstanding debt with accrued interest	49,624				42,090				49,624	42,090
Restricted cash
Restricted cash, current portion	1,092				901				1,092	901
Restricted cash, long term portion	$ 342				$ 683				$ 342	$ 683
"First Space" Sublease
Restricted cash
Restricted cash														$ 800
"Second Space" Sublease
Restricted cash
Restricted cash												$ 300

Summary of Significant Accoun39

Summary of Significant Accounting Policies - Concentration (Details) - customer	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Sales | Customer
Risk and Uncertainties
Number of customers exceeding 10% of benchmark	0	0	0
Accounts Receivable | Customer
Risk and Uncertainties
Number of customers exceeding 10% of benchmark	1
Concentration risk (as a percent)	52.00%
Accounts Receivable | Credit
Risk and Uncertainties
Number of customers exceeding 10% of benchmark		0

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of Significant Accounting Policies
Advertising costs	$ 0.4	$ 1.1	$ 1.1
Shipping and handling costs	8.2	7	4.5
Capitalized software	1.3	0.8
Amortized expense	$ 0.6	$ 0.2	$ 0

Summary of Significant Accoun41

Summary of Significant Accounting Policies - AOCL (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ 725	$ 1,416
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification adjustment	$ 200	$ 0	$ 0

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Property (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property and Equipment
Estimated useful life									P3Y
Gain (loss) from operations									$ (96,488)	$ (59,838)	$ 665
Increase (decrease) in net loss	$ 37,907	$ 26,017	$ 23,156	$ 8,685	$ 22,960	$ 17,630	$ 19,681	$ 10,004	$ 95,765	$ 70,275	$ 5,152
Increase (decrease) in basic and diluted loss per share (in dollars per share)	$ 0.72	$ 0.50	$ 0.46	$ 0.17	$ 0.47	$ 0.39	$ 3.58	$ 1.89	$ 1.86	$ 2.68	$ 1.07
Impairment of assets									$ 2,138	$ 1,557
Machinery and equipment
Property and Equipment
Estimated useful life							P3Y
Impairment of assets									2,100
Machinery and equipment | Change to estimated useful life
Property and Equipment
Estimated useful life							P5Y
Increase (decrease) in net loss									$ 1,700	$ (1,700)
Increase (decrease) in basic and diluted loss per share (in dollars per share)									$ 0.04	$ (0.07)

Summary of Significant Accoun43

Summary of Significant Accounting Policies - Inventory (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Summary of Significant Accounting Policies
Loss on write down of inventory	$ 2,110

Fair Value Measurements - Hiera

Fair Value Measurements - Hierarchy (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Transfers between Levels 1 and 2
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	$ 0	$ 0
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	0	0
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount	0	0
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount	0	0
Transfers into and out of Level 3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3	0	0
Recurring
Financial Assets:
Total financial assets	141,637,000	207,552,000
Current Liabilities:
Warrants	3,792,000	3,649,000
Total financial liabilities	3,792,000	3,649,000
Recurring | Money market deposits
Financial Assets:
Total financial assets	10,777,000	5,966,000
Recurring | U.S. Treasury securities
Financial Assets:
Total financial assets	57,442,000	103,813,000
Recurring | U.S. agency securities
Financial Assets:
Total financial assets	56,114,000	78,853,000
Recurring | Municipal securities
Financial Assets:
Total financial assets	17,304,000	18,920,000
Recurring | Level 1
Financial Assets:
Total financial assets	68,219,000	109,779,000
Recurring | Level 1 | Money market deposits
Financial Assets:
Total financial assets	10,777,000	5,966,000
Recurring | Level 1 | U.S. Treasury securities
Financial Assets:
Total financial assets	57,442,000	103,813,000
Recurring | Level 2
Financial Assets:
Total financial assets	73,418,000	97,773,000
Recurring | Level 2 | U.S. agency securities
Financial Assets:
Total financial assets	56,114,000	78,853,000
Recurring | Level 2 | Municipal securities
Financial Assets:
Total financial assets	17,304,000	18,920,000
Recurring | Level 3
Current Liabilities:
Warrants	3,792,000	3,649,000
Total financial liabilities	$ 3,792,000	$ 3,649,000

Fair Value Measurements - Level

Fair Value Measurements - Level III (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Long-term Debt | Secured Loan Arrangement
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		$ 20,964
Settled		(20,000)
Long-term Debt | Nonperating Expenses | Secured Loan Arrangement
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in fair value		(964)
Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 3,649	2,232
Settled		(240)
Change in fair value	143	1,657
Ending balance	$ 3,792	$ 3,649

Fair Value Measurements - Assum

Fair Value Measurements - Assumptions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)company	Dec. 31, 2015company
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Volatility, basket of companies | company	4	15
Warrants
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Warrants	$ 3,792
Volatility (as a percent)	61.30%
Warrant valuation increase	$ 100

Financial Instruments (Details)

Financial Instruments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)position	Dec. 31, 2015USD ($)
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Estimated Fair Value	$ 130,860	$ 201,586
Realized gain	$ 200	0
Number of investments, unrealized loss position | position	27
Interest income	$ 1,500
Amortized Cost
Less than one year	48,265
Greater than one year but less than five years	83,320
Total	131,585
Fair Value
Less than one year	48,212
Greater than one year but less than five years	82,648
Total	130,860
Available-for-sale securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	142,362	208,968
Unrealized Gain		3
Unrealized Loss	(725)	(1,419)
Estimated Fair Value	141,637	207,552
Money market deposits
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	10,777	5,966
Estimated Fair Value	10,777	5,966
U.S. Treasury securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	57,846	104,537
Unrealized Gain		1
Unrealized Loss	(404)	(725)
Estimated Fair Value	57,442	103,813
U.S. agency securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	56,261	79,491
Unrealized Loss	(147)	(638)
Estimated Fair Value	56,114	78,853
Municipal securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Cost	17,478	18,974
Unrealized Gain		2
Unrealized Loss	(174)	(56)
Estimated Fair Value	17,304	18,920
Cash equivalents | Available-for-sale securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Estimated Fair Value	10,777	5,966
Short-term investments | Available-for-sale securities
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Estimated Fair Value	$ 130,860	$ 201,586

Balance Sheet Components - Allo

Balance Sheet Components - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts
Beginning balance	$ 971	$ 527
Provision for estimated bad debts	984	529	$ 349
Write offs	(65)	(85)
Ending balance	$ 1,890	$ 971	$ 527

Balance Sheet Components - Prop

Balance Sheet Components - Property (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property and Equipment, net
Property and equipment, gross		$ 26,500	$ 51,626	$ 26,500
Less: Accumulated depreciation and amortization		(13,790)	(19,337)	(13,790)
Total Property and Equipment, net		12,710	32,289	12,710
Impairment of assets			2,138	1,557
Proceeds from sale of impaired machinery and equipment				463	$ 15
Machinery and equipment
Property and Equipment, net
Property and equipment, gross		20,670	27,303	20,670
Impairment of assets			2,100
Proceeds from sale of impaired machinery and equipment	$ 200	500
Asset held for sale		200		200
Machinery and equipment | Cost of product, licensing and other revenues
Property and Equipment, net
Impairment of assets				1,000
Machinery and equipment | General and administrative expense
Property and Equipment, net
Impairment of assets			200
Machinery and equipment | Maintenance service contract
Property and Equipment, net
Impairment of assets			300
Furniture and fixtures
Property and Equipment, net
Property and equipment, gross		217	$ 1,087	217
Useful Life			3 years
Computer equipment
Property and Equipment, net
Property and equipment, gross		911	$ 861	911
Useful Life			3 years
Capitalized software held for internal use
Property and Equipment, net
Property and equipment, gross		1,037	$ 2,172	1,037
Useful Life			3 years
Leasehold improvements
Property and Equipment, net
Property and equipment, gross		1,686	$ 10,444	1,686
Construction-in-process
Property and Equipment, net
Property and equipment, gross		$ 1,979	$ 9,759	$ 1,979
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) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Balance Sheet Components
Agreement term	4 years
Total consideration	$ 3.2
Deferred costs included in other long-term assets	2.6
Amortization of deferred costs	$ 0.6

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Compensation (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Balance Sheet Components
Accrued paid time off	$ 1,892	$ 2,024
Accrued commissions	3,868	3,691
Accrued bonuses	2,387	1,348
Other accrued compensation	2,920	1,489
Total accrued compensation	$ 11,067	$ 8,552

Balance Sheet Components - Ot52

Balance Sheet Components - Other Accured Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Balance Sheet Components
Overpayments from insurance carriers	$ 7,535	$ 3,306
Other accrued expenses	4,521	4,344
Testing and laboratory materials from suppliers	3,804	7,736
Marketing and corporate affairs	202	1,118
Leasehold improvement projects in progress	1,659
Accrued specimen service fees	469	454
Accrued shipping charges	467	401
Sales tax payable	459	346
Clinical trials and studies	388	90
Accrued rent	195	450
Legal, audit and consulting fees	180	421
Deferred lease obligation		42
Total other accrued liabilities	$ 19,879	$ 18,708

Commitments and Contingencies53

Commitments and Contingencies (Details)	1 Months Ended	12 Months Ended
	Oct. 31, 2014USD ($)ft²item	Dec. 31, 2016USD ($)ft²leaseitem	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Mar. 31, 2014USD ($)	Jan. 31, 2013USD ($)
Operating Leases
Leasehold improvements		$ 5,400,000
Future minimum lease payments
2,017		6,914,000
2,018		6,914,000
2,019		6,413,000
2,020		6,313,000
2,021		6,313,000
2022 and thereafter		15,622,000
Total future minimum lease payment		48,489,000
Rent expense		$ 5,400,000	$ 2,700,000	$ 1,500,000
Corporate Headquarters Lease
Operating Leases
Office space (area) | ft²		88,000
Number of subleases | lease		2
Number of letters of credit | item		2
"First Space" Sublease
Operating Leases
Office space (area) | ft²		61,000
Restricted cash						$ 800,000
"Second Space" Sublease
Operating Leases
Office space (area) | ft²		27,000
Restricted cash					$ 300,000
Corporate Headquarters Sublease
Operating Leases
Office space (area) | ft²	48,000
Term of lease	84 months
Number of sublease phases | item	2
Sublease, First Phase
Operating Leases
Office space (area) | ft²	16,000
Monthly base rent	$ 60,730
Sublease, Second Phase
Operating Leases
Office space (area) | ft²	32,000
Monthly base rent	$ 121,460
Redwood City Lease
Operating Leases
Monthly base rent		$ 100,000
Security deposit		$ 100,000
Austin TX, Long-term Lease
Operating Leases
Office space (area) | ft²		94,000
Term of lease		132 months
Monthly base rent		$ 100,000
Maximum monthly base rent after escalation		200,000
Security deposit		400,000
Allowance for leasehold improvements		$ 7,800,000

Commitments and Contingencies -

Commitments and Contingencies - Legal (Details) - USD ($) $ in Millions	Jun. 02, 2015	Aug. 31, 2015	Dec. 31, 2016
Other commitments
Shareholders (as a percent)			5.00%
Supplier One | Inventory Material
Other commitments
Purchase commitment			$ 5.1
Supplier Two | Inventory Material
Other commitments
Purchase commitment			3.4
Supplier Three
Other commitments
Purchase commitment			3
Securities related claims
Other commitments
Estimate of possible loss			1.5
Commercial general liability claims
Other commitments
Estimate of possible loss			$ 0.3
Third-party payer
Other commitments
Amount sought	$ 1.9
Settlement amount		$ 1.2

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) $ / shares in Units, $ in Thousands	1 Months Ended		5 Months Ended	6 Months Ended	12 Months Ended
	Feb. 29, 2016shares	Jun. 30, 2015shares	Apr. 30, 2016USD ($)shares	Oct. 31, 2016USD ($)shares	Dec. 31, 2016USD ($)$ / sharesperiodshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)
Stock Based Compensation
Proceeds from issuance of common stock under employee stock purchase plan | $					$ 2,589
2015 Plan
Stock Based Compensation
Shares reserved for issuance		3,451,495			13,094,869
Shares reserved for issuance as a proportion common stock outstanding (as a percent)					4.00%
2015 Plan | Minimum
Stock Based Compensation
Shares reserved for issuance					3,500,000
2007 Plan
Stock Based Compensation
Shares reserved for issuance					7,713,510
Employee stock purchase plan
Stock Based Compensation
Shares reserved for issuance		893,548			1,056,344
Shares reserved for issuance as a proportion common stock outstanding (as a percent)					1.00%
Price in relation to fair market value of common stock on the date of grant, lower range limit (as a percent)					85.00%
Maximum offering period, term					27 months
Number of expected offering periods each year | period					2
Offering period, expected term					6 months
Issuance of common stock under employee stock purchase plan (in shares)			116,215	224,637
Proceeds from issuance of common stock under employee stock purchase plan | $			$ 1,000	$ 1,600
Employee stock purchase plan | Minimum
Stock Based Compensation
Shares reserved for issuance					880,000
Employee and non-employee stock options
Stock Based Compensation
Stock based compensation expense | $					$ 10,601	$ 7,326	$ 5,157
Shares available for issuance					4,115,000	3,743,000
Employee and non-employee stock options | 2015 Plan
Stock Based Compensation
Vesting period					4 years
Expiration period		10 years
Employee and non-employee stock options | 2007 Plan
Stock Based Compensation
Vesting period					4 years
Expiration period					10 years
Stock options, exercise price range, number outstanding (in shares)					6,098,564
Stock options, exercise price range, lower range limit (in dollars per share) | $ / shares					$ 0.0978
Stock options, exercise price range, upper range limit (in dollars per share) | $ / shares					12.8501
Stock options, exercise price range, weighted-average exercise price (in dollars per share) | $ / shares					$ 2.71
Shares exercised and unvested						1,300,000
Period after Market Stand-off repurchase right expires						210 days
Accelerated stock-based compensation expense | $						$ 1,300
Stock appreciation rights | 2015 Plan
Stock Based Compensation
Vesting period					4 years
Expiration period					10 years
Restricted shares | Non-employee service provider
Stock Based Compensation
Shares granted	24,540
Restricted stock units
Stock Based Compensation
Shares granted					212,000

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options (Details) - Employee and non-employee stock options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock Based Compensation
Shares available for grant, beginning balance	3,743
Additional shares authorized	2,014
Options granted (in shares)	(2,558)
Options forfeited (in shares)	916
Shares available for grant, end balance	4,115	3,743
Number of shares
Outstanding, beginning balance (in shares)	9,316
Options granted (in shares)	2,558
Options exercised (in shares)	(1,915)
Options forfeited (in shares)	(916)
Outstanding, end balance (in shares)	9,043	9,316
Exercisable (in shares)	5,054
Vested and expected to vest (in shares)	9,039
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 3.96
Granted (in dollars per share)	10.23
Exercised (in dollars per share)	1.88
Forfeited (in dollars per share)	8.28
Outstanding, end balance (in dollars per share)	5.72	$ 3.96
Exercisable (in dollars per share)	3.10
Vested and expected to vest (in dollars per share)	$ 5.72
Additional disclosures
Weighted average contractual term, options outstanding	7 years 6 months 18 days	8 years 3 months 22 days
Exercisable (in years)	6 years 6 months 4 days
Vested and expected to vest (in years)	7 years 6 months 18 days
Aggregate intrinsic value, options outstanding	$ 55,396	$ 63,713
Aggregate intrinsic value, options exercisable	43,938
Aggregate intrinsic value, vested and expected to vest	55,386
Aggregate intrinsic value, options exercised	16,900	6,900	$ 1,200
Fair value, options vested	$ 8,500	$ 4,500	$ 4,100
Weighted-average grant date fair value, options granted	$ 5.92	$ 7.29	$ 3.28

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units (Details) - Restricted stock units shares in Thousands	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Shares
Balance (in shares) | shares
Granted (in shares) | shares	212
Vested (in shares) | shares	(40)
Canceled/forfeited (in shares) | shares	(13)
Balance (in shares) | shares	159
Weighted Average Grant Date Fair Value
Balance (in dollars per share) | $ / shares
Granted (in dollars per share) | $ / shares	9.76
Vested (in dollars per share) | $ / shares	9.59
Canceled/forfeited (in dollars per share) | $ / shares	9.81
Balance (in dollars per share) | $ / shares	$ 9.80

Stock-Based Compensation - Comp

Stock-Based Compensation - Compensation Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee and non-employee stock options
Stock based compensation expense
Options granted (in shares)		2,558,000
Stock based compensation expense		$ 10,601	$ 7,326	$ 5,157
Unrecognized compensation expense	$ 19,400	$ 19,400
Unrecognized compensation expense recognized over weighted average period		2 years 9 months 18 days
Employee and non-employee stock options | Cost of product, licensing and other revenues
Stock based compensation expense
Stock based compensation expense		$ 641	592	291
Employee and non-employee stock options | Research and development
Stock based compensation expense
Stock based compensation expense		2,853	1,575	1,593
Employee and non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock based compensation expense		7,107	5,159	3,273
Employee stock options
Stock based compensation expense
Stock based compensation expense		10,317	6,910	5,005
Employee stock options | Cost of product, licensing and other revenues
Stock based compensation expense
Stock based compensation expense		651	351	262
Employee stock options | Research and development
Stock based compensation expense
Stock based compensation expense		2,829	1,566	1,563
Employee stock options | Selling, general and administrative
Stock based compensation expense
Stock based compensation expense		$ 6,837	4,993	3,180
Non-employee stock options
Stock based compensation expense
Options granted (in shares)	141,046
Options unvested (in shares)	10,456	10,456
Stock based compensation expense		$ 284	416	152
Non-employee stock options | Cost of product, licensing and other revenues
Stock based compensation expense
Stock based compensation expense		(10)	241	29
Non-employee stock options | Research and development
Stock based compensation expense
Stock based compensation expense		24	9	30
Non-employee stock options | Selling, general and administrative
Stock based compensation expense
Stock based compensation expense		$ 270	$ 166	$ 93

Stock-Based Compensation - Assu

Stock-Based Compensation - Assumptions (Details) - shares	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee and non-employee stock options
Stock Based Compensation
Options granted (in shares)		2,558,000
Employee stock options
Valuation of Stock Option Grants to Employees
Expected volatility, minimum		62.20%	69.70%	73.40%
Expected volatility, maximum		72.50%	78.80%	87.00%
Expected dividend rate		0.00%	0.00%	0.00%
Risk free interest rate, minimum		0.97%	1.56%	1.65%
Risk free interest rate, maximum		1.92%	2.32%	2.04%
Employee stock options | Minimum
Valuation of Stock Option Grants to Employees
Expected term		5 years 1 month 6 days	5 years 7 months 6 days	4 years 10 months 24 days
Employee stock options | Maximum
Valuation of Stock Option Grants to Employees
Expected term		5 years 2 months 12 days	10 years	7 years 1 month 6 days
Non-employee stock options
Stock Based Compensation
Options granted (in shares)	141,046
Options unvested (in shares)	10,456	10,456
Valuation of Stock Option Grants to Employees
Expected volatility, minimum		50.90%	70.20%	71.90%
Expected volatility, maximum		72.60%	75.40%	80.20%
Expected dividend rate		0.00%	0.00%	0.00%
Risk free interest rate, minimum		0.68%	1.74%	1.41%
Risk free interest rate, maximum		1.38%	2.24%	2.61%
Non-employee stock options | Minimum
Valuation of Stock Option Grants to Employees
Expected term		2 years 8 months 12 days	4 years 10 months 24 days	4 years 4 months 24 days
Non-employee stock options | Maximum
Valuation of Stock Option Grants to Employees
Expected term		3 years 2 months 12 days	9 years 9 months 18 days	10 years

Debt (Details)

Debt (Details) $ / shares in Units, $ in Thousands	1 Months Ended						12 Months Ended
	Jun. 30, 2016USD ($)	Nov. 30, 2015USD ($)	Oct. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2014USD ($)item	Apr. 30, 2013USD ($)$ / sharesshares	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)item	Apr. 30, 2014$ / shares	Dec. 31, 2007$ / shares
Debt Instrument [Line Items]
Interest expense							$ 533	$ 3,505	$ 4,219
Royalty due							$ 1,800
Exercise price of warrants (in dollars per share) | $ / shares											$ 0.0978
Repayments of equipment financing								$ 5,850	$ 2,480
Secured Loan Arrangement
Debt Instrument [Line Items]
Repayments			$ 28,000
Effective interest rate (as a percent)							20.90%	19.80%
Number of shares of common stock that may be called by warrants | shares						376,691
Exercise price of warrants (in dollars per share) | $ / shares						$ 2.3229				$ 2.3229
Prepayment premium (as a percent)						10.00%
Amount paid to extinguish debt			28,000
Credit Agreement
Debt Instrument [Line Items]
Borrowing capacity						$ 40,000
Borrowings						$ 20,000
Base interest rate (as a percent)						1.00%
Spread on base interest rate (as a percent)						8.00%
Interest expense							$ 1,400	$ 1,800
Credit Agreement | Minimum
Debt Instrument [Line Items]
Interest rate (as a percent)						9.00%
Royalty Agreement
Debt Instrument [Line Items]
Royalty payment percentage owed on fiscal year revenues up to threshold						1.00%
Revenue threshold amount for determination of royalty payment percentage						$ 50,000
Royalty payment percentage owed on fiscal year revenues in excess of threshold						1.50%
Interest expense							7,100	2,200
Line Of Credit-UBS
Debt Instrument [Line Items]
Borrowing capacity				$ 50,000
Borrowings	$ 8,000	$ 10,000	$ 32,000
Repayments	1,000
Remaining borrowing capacity							400
Outstanding balance							49,600
Interest expense								$ 100
Effective interest rate (as a percent)		0.85%	0.84%
Accrued interest							$ 600
Amount paid to extinguish debt	$ 1,000
Line Of Credit-UBS | 30-day LIBOR
Debt Instrument [Line Items]
Spread on variable rate (as a percent)				0.65%
Equipment Financing Facility
Debt Instrument [Line Items]
Borrowing capacity						$ 5,000
Borrowings					$ 5,900
Effective interest rate (as a percent)					6.35%	7.35%			6.35%
Number of payment installments | item					30				30
Repayments of equipment financing				$ 4,100
Equipment Financing Facility | 30-day LIBOR
Debt Instrument [Line Items]
Spread on variable rate (as a percent)						2.50%
Equipment Financing Facility | Prime
Debt Instrument [Line Items]
Spread on variable rate (as a percent)					3.10%	4.10%

Warrants (Details)

Warrants (Details) - $ / shares	1 Months Ended		12 Months Ended
	Dec. 31, 2015	Jul. 31, 2015	Dec. 31, 2015	Nov. 20, 2014	Nov. 19, 2014	Apr. 30, 2014	Apr. 30, 2013	Dec. 31, 2009	Dec. 31, 2007
Class of Stock [Line Items]
Warrants outstanding (in shares)									24,538
Warrants exercise price (in dollars per share)									$ 0.0978
Secured Loan Arrangement
Class of Stock [Line Items]
Warrants outstanding (in shares)						376,691
Warrants exercise price (in dollars per share)						$ 2.3229	$ 2.3229
B
Class of Stock [Line Items]
Warrants outstanding (in shares)								33,742
Warrants exercise price (in dollars per share)								$ 1.8908
E
Class of Stock [Line Items]
Warrants outstanding (in shares)				429,440
Warrants exercise price (in dollars per share)				$ 0.0163
Liquidation preference to liquidation value in the agreement (as a percent)				1.00%	2.00%
Common stock
Class of Stock [Line Items]
Closing price (in dollars per share)	$ 11.57		$ 11.57
Conversion into common shares (in shares)			31,397,000
Common stock | B
Class of Stock [Line Items]
Common stock issued for each warrant (in shares)		1
Conversion into common shares (in shares)	28,227
Common stock | E
Class of Stock [Line Items]
Conversion into common shares (in shares)		429,042

Convertible Preferred Stock (De

Convertible Preferred Stock (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Jul. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock
Common stock, shares authorized	750,000,000	750,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	50,000,000	50,000,000		51,233
Convertible preferred stock, shares outstanding		0	31,397,221	31,397
Liquidation Amount				$ 133,757
Proceeds, net of Issuance Costs				240,612
Convertible preferred stock
Stock
Proceeds, net of Issuance Costs				$ 240,612,000	$ 185,199,000
A1
Stock
Preferred stock, shares authorized				5,000
Convertible preferred stock, shares outstanding				3,067
Liquidation Amount				$ 20
Proceeds, net of Issuance Costs				$ 20
A
Stock
Preferred stock, shares authorized				8,173
Convertible preferred stock, shares outstanding				5,014
Liquidation Amount				$ 4,005
Proceeds, net of Issuance Costs				$ 3,927
B
Stock
Preferred stock, shares authorized				5,745
Convertible preferred stock, shares outstanding				3,491
Liquidation Amount				$ 6,600
Proceeds, net of Issuance Costs				$ 6,569
C
Stock
Preferred stock, shares authorized				8,941
Convertible preferred stock, shares outstanding				5,485
Liquidation Amount				$ 12,160
Proceeds, net of Issuance Costs				$ 58,876
D
Stock
Preferred stock, shares authorized				6,694
Convertible preferred stock, shares outstanding				4,107
Liquidation Amount				$ 20,047
Proceeds, net of Issuance Costs				$ 80,788
E
Stock
Preferred stock, shares authorized				9,592
Convertible preferred stock, shares outstanding				5,884
Liquidation Amount				$ 35,425
Proceeds, net of Issuance Costs				$ 35,019
F
Stock
Preferred stock, shares authorized				7,088
Convertible preferred stock, shares outstanding				4,349
Liquidation Amount				$ 55,500
Proceeds, net of Issuance Costs				$ 55,413

Common Stock (Details)

Common Stock (Details) shares in Thousands	Jun. 19, 2015	Dec. 31, 2016item$ / sharesshares	Dec. 31, 2015item$ / sharesshares
Common Stock.
Authorized common stock (in shares)		750,000	750,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001	$ 0.0001
Common stock outstanding (in shares)		52,665	50,346
Number of votes | item		1	1
Stock split conversion	0.6135

Income Taxes - Effective Tax Ra

Income Taxes - Effective Tax Rates (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Effective tax rates differing from U.S. federal statutory rate
U.S. Federal taxes (Benefit) at statutory rate			$ (32,277,000)	$ (24,375,000)
State tax expense			(2,842,000)	(2,428,000)
Research and development credits			(1,449,000)	(751,000)
Stock-based compensation			1,275,000	1,683,000
Mark to market fair value adjustments			49,000	504,000
Other nondeductible items			933,000	841,000
Change in valuation allowance			34,453,000	$ 24,526,000
Provision for income taxes	$ 39,000	$ 103,000	$ 142,000
U.S. Federal taxes (Benefit) at statutory rate (as a percent)			(34.00%)	(34.00%)
State tax expense (as a percent)			(2.99%)	(3.39%)
Research and development credits (as a percent)			(1.53%)	(1.05%)
Stock-based compensation (as a percent)			1.34%	2.35%
Mark to market fair value adjustments (as a percent)			0.05%	0.70%
Other nondeductible items (as a percent)			0.99%	1.17%
Change in valuation allowance (as a percent)			36.29%	34.21%
Provision for income taxes (as a percent)			0.15%
Foreign withholding tax			$ 142,000

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes
Valuation allowance increase	$ 34,500	$ 24,500	$ 900
Deferred tax assets
Net operating loss carryforwards	68,504	41,451
Research and development tax credit carryforwards	8,634	4,794
Reserves and accruals	5,719	3,108
Stock based compensation	3,220	2,206
Total deferred tax assets before valuation allowance	86,077	51,559
Less: valuation allowance	(85,606)	(51,153)
Deferred tax assets, net	471	406
Deferred tax liabilities
Property and equipment	$ (471)	$ (406)

Income Taxes - Net Operating Lo

Income Taxes - Net Operating Loss Carryforwards (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Operating Loss Carryforwards [Line Items]
Excess tax benefits from employee stock option exercises, equity increase	$ 7.2
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	205.3
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 109.6

Income Taxes - Tax Credit Carry

Income Taxes - Tax Credit Carryforwards (Details) $ in Millions	Dec. 31, 2016USD ($)
Tax Credit Carryforward [Line Items]
Taxable income required for full realization of deferred tax assets	$ 226.2
Federal | Research and development tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	8.5
State | Research and development tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 5.8

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Interest and penalties accrued	$ 0
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Balance at beginning of year	2,405	$ 1,360
Additions based on tax positions related to the current year	1,836	1,045
Additions for tax positions of prior years	52
Balance at end of year	4,293	2,405
Research and development tax credit carryforward
Unrecognized tax benefits increased	$ 1,900	$ 1,000

Related-Party Transactions (Det

Related-Party Transactions (Details) - Notes Receivable from Officers	1 Months Ended
	Apr. 30, 2012USD ($)
Dr Rabinowitz
Related-Party Transactions
Note receivable	$ 154,000
Note receivable interest rate (as a percent)	1.15%
Mr Sheena
Related-Party Transactions
Note receivable	$ 38,280
Note receivable interest rate (as a percent)	1.15%

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								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Basic and diluted loss per share:
Net loss	$ (37,907)	$ (26,017)	$ (23,156)	$ (8,685)	$ (22,960)	$ (17,630)	$ (19,681)	$ (10,004)	$ (95,765)	$ (70,275)	$ (5,152)
Weighted-average common shares outstanding									51,667	27,687	6,670
Less: weighted-average unvested common shares subject to repurchase									(91)	(1,483)	(1,870)
Weighted-average number of shares used in computing net loss per share, basic and diluted									51,576	26,204	4,800
Basic and diluted net loss per share (in dollars per share)	$ (0.72)	$ (0.50)	$ (0.46)	$ (0.17)	$ (0.47)	$ (0.39)	$ (3.58)	$ (1.89)	$ (1.86)	$ (2.68)	$ (1.07)

Net Loss per Share - Potentiall

Net Loss per Share - Potentially Dilutive Shares (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations	9,669	11,000	42,401
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	9,043	9,316	8,450
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations	377	377	864
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations	159
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	90
Common stock subject to repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations		1,307	1,690
Redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive shares not included in diluted per share calculations			31,397

Geographic Information (Details

Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 49,299	$ 53,889	$ 51,984	$ 61,902	$ 52,912	$ 44,921	$ 45,087	$ 47,435	$ 217,074	$ 190,355	$ 159,289
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									193,054	164,952	136,478
Americas, excluding U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									2,562	4,552	4,883
Europe, Middle East, India, Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									14,256	15,437	13,098
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 7,202	$ 5,414	$ 4,830

Quarterly Financial Data (Detai

Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating results:
Total revenues	$ 49,299	$ 53,889	$ 51,984	$ 61,902	$ 52,912	$ 44,921	$ 45,087	$ 47,435	$ 217,074	$ 190,355	$ 159,289
Cost of product, licensing and other revenues	38,000	34,261	30,973	32,340	31,814	30,456	25,732	24,843	135,574	112,845	78,396
Gross profit	11,299	19,628	21,011	29,562	21,098	14,465	19,355	22,592
Other costs and expenses	49,012	46,283	43,526	39,167	38,446	35,206	34,827	28,869
Interest expense and other (expense) income, net	(155)	741	(641)	920	(5,612)	3,111	(4,209)	(3,727)
Income tax expense	(39)	(103)							(142)
Net loss	$ (37,907)	$ (26,017)	$ (23,156)	$ (8,685)	$ (22,960)	$ (17,630)	$ (19,681)	$ (10,004)	$ (95,765)	$ (70,275)	$ (5,152)
Per share data:
Basic and diluted net loss per share (in dollars per share)	$ (0.72)	$ (0.50)	$ (0.46)	$ (0.17)	$ (0.47)	$ (0.39)	$ (3.58)	$ (1.89)	$ (1.86)	$ (2.68)	$ (1.07)

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event	1 Months Ended
	Jan. 31, 2017USD ($)
Subsequent Event [Line Items]
Amended agreement, number of vendors	$ 1
Minimum purchase commitment amount for 2017	3,600,000
Minimum purchase commitment amount for 2018	$ 4,500,000

Uncategorized Items - ntra-2016

Label	Element	Value
Convertible Preferred Stock [Member]
Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments	us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecuritiesNetOfAdjustments	$ (240,585,000)
Temporary Equity Issuance Costs	ntra_TemporaryEquityIssuanceCosts	$ 27,000
Stock Issued During Period, Shares, Conversion of Convertible Securities	us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities	(31,397,000)