NanoString (NSTG) 10-K 7 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 28, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	NSTG
Entity Registrant Name	NANOSTRING TECHNOLOGIES INC
Entity Central Index Key	1,401,708
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		25,440,469
Entity Public Float			$ 347.3

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 26,136	$ 20,583
Short-term investments	51,419	53,453
Accounts receivable, net	19,564	22,193
Inventory, net	20,057	13,812
Prepaid expenses and other current assets	4,745	3,744
Total current assets	121,921	113,785
Restricted cash	143	143
Property and equipment, net	14,057	12,158
Other assets	641	287
Total assets	136,762	126,373
Current liabilities:
Accounts payable	4,092	4,935
Accrued liabilities	4,507	3,494
Employee-related Liabilities, Current	8,634	8,240
Customer Deposits, Current	8,945	610
Deferred revenue, current portion	9,229	19,033
Deferred rent, current portion	512	13
Lease financing obligations, current portion	0	58
Total current liabilities	35,919	36,383
Deferred revenue, net of current portion	3,304	22,664
Deferred rent and other liabilities, net of current portion	8,499	7,655
Long-term debt and lease financing obligations, net of current portion and debt issuance costs	48,931	47,366
Total liabilities	96,653	114,068
Commitments and contingencies (Note 13)
Stockholders’ equity
Preferred stock, $0.0001 par value, 15,000 shares authorized; none issued	0	0
Common stock, $0.0001 par value, 150,000 shares authorized; 25,421 and 21,528 shares issued and outstanding at December 31, 2017 and 2016, respectively	2	2
Additional paid-in-capital	353,308	281,900
Other comprehensive loss	(99)	(57)
Accumulated deficit	(313,102)	(269,540)
Total stockholders’ equity	40,109	12,305
Total liabilities and stockholders’ equity	$ 136,762	$ 126,373

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	15,000,000	15,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	25,421,000	21,528,000
Common stock, shares outstanding (in shares)	25,421,000	21,528,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Product and service	$ 72,010	$ 69,134	$ 56,639
Collaboration	42,895	17,355	6,028
Total revenue	114,905	86,489	62,667
Costs and expenses:
Cost of product and service revenue	31,880	30,245	26,126
Research and development	46,888	34,720	24,597
Selling, general and administrative	74,334	62,700	53,186
Total costs and expenses	153,102	127,665	103,909
Loss from operations	(38,197)	(41,176)	(41,242)
Other income (expense):
Interest income	809	390	233
Interest expense	(6,153)	(5,672)	(4,017)
Other income (expense)	183	(515)	(389)
Total other income (expense)	(5,161)	(5,797)	(4,173)
Net loss before provision for income taxes	(43,358)	(46,973)	(45,415)
Provision for income taxes	(204)	(116)	(166)
Net loss	$ (43,562)	$ (47,089)	$ (45,581)
Net loss per share-basic and diluted (in dollars per share)	$ (1.84)	$ (2.34)	$ (2.40)
Weighted average shares used in computing basic and diluted net loss per share (in shares)	23,731	20,116	19,027

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (43,562)	$ (47,089)	$ (45,581)
Other comprehensive income (loss):
Change in unrealized gain (loss) on short-term investments	(42)	(28)	14
Comprehensive loss	$ (43,604)	$ (47,117)	$ (45,567)

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Other Comprehensive Loss	Accumulated Deficit
Balance at (in shares) at Dec. 31, 2014		18,272
Balances at at Dec. 31, 2014	$ 44,813	$ 2	$ 221,724	$ (43)	$ (176,870)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock net of issuance costs (in shares)		960
Issuance of common stock net of issuance costs	12,518	$ 0	12,518
Issuance of common stock warrants	0
Issuance of common stock for employee stock purchase plan (in shares)		136
Issuance of common stock for employee stock purchase plan	1,295		1,295
Exercise of stock options (in shares)		202
Exercise of stock options	876		876
Exercise of common stock warrant, net (in shares)		0
Exercise of common stock warrants, net	2		2
Stock-based compensation	6,278		6,278
Net loss	(45,581)				(45,581)
Other comprehensive loss	14			14
Balance at (in shares) at Dec. 31, 2015		19,570
Balances at at Dec. 31, 2015	20,215	$ 2	242,693	(29)	(222,451)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock net of issuance costs (in shares)		1,333
Issuance of common stock net of issuance costs	26,073		26,073
Issuance of common stock warrants	0
Issuance of common stock for employee stock purchase plan (in shares)		139
Issuance of common stock for employee stock purchase plan	1,489		1,489
Exercise of stock options (in shares)		349
Exercise of stock options	2,607		2,607
Exercise of common stock warrant, net (in shares)		133
Exercise of common stock warrants, net	0		0
Vesting of restricted stock units (in shares)		5
Stock-based compensation	9,038		9,038
Net loss	(47,089)				(47,089)
Other comprehensive loss	(28)			(28)
Balance at (in shares) at Dec. 31, 2016		21,529
Balances at at Dec. 31, 2016	12,305	$ 2	281,900	(57)	(269,540)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock net of issuance costs (in shares)		3,450
Issuance of common stock net of issuance costs	56,486		56,486
Issuance of common stock warrants	674		674
Issuance of common stock for employee stock purchase plan (in shares)		139
Issuance of common stock for employee stock purchase plan	$ 1,793		1,793
Exercise of stock options (in shares)	227,696	228
Exercise of stock options	$ 1,086		1,086
Exercise of common stock warrant, net (in shares)		29
Exercise of common stock warrants, net	0
Vesting of restricted stock units (in shares)		46
Stock-based compensation	11,369		11,369
Net loss	(43,562)
Other comprehensive loss	(42)			(42)
Balance at (in shares) at Dec. 31, 2017		25,421
Balances at at Dec. 31, 2017	$ 40,109	$ 2	$ 353,308	$ (99)	$ (313,102)

Consolidated Statements of Cha7

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Additional Paid-in Capital
Issuance cost	$ 1,300	$ 1,000	$ 500

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net loss	$ (43,562)	$ (47,089)	$ (45,581)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	3,354	2,977	2,377
Stock-based compensation expense	11,369	9,038	6,278
Amortization (accretion) of discount or premium on short-term investments	198	(20)	270
Interest accrued on long-term debt	171	158	18
Conversion of accrued interest to long-term debt	1,472	1,357	1,067
(Gain) loss on disposal of property and equipment	15	(2)	3
Provision for bad debt	361	0	34
Provision for inventory obsolescence	866	822	248
Changes in operating assets and liabilities
Accounts receivable	2,277	(2,476)	(7,328)
Inventory	(8,742)	(5,857)	(5,602)
Prepaid expenses and other	(911)	72	1,199
Other assets	(367)	37	(7)
Accounts payable	(110)	869	(166)
Accrued liabilities	1,312	(40)	(80)
Accrued compensation and other employee benefits	295	281	1,242
Customer deposits	8,335	610	0
Deferred revenue	(29,161)	29,948	(127)
Deferred rent and other liabilities	1,171	3,236	2,793
Net cash used in operating activities	(51,657)	(6,079)	(43,362)
Investing activities
Purchases of property and equipment	(4,284)	(3,991)	(3,796)
Proceeds from sale of property and equipment	0	4	6
Proceeds from sale of short-term investments	3,600	4,700	3,000
Proceeds from maturity of short-term investments	79,599	34,800	57,309
Purchases of short-term investments	(81,405)	(65,774)	(32,750)
Net cash (used in) provided by investing activities	(2,490)	(30,261)	23,769
Financing activities
Proceeds from long-term debt	0	5,000	10,000
Repayment of long-term debt and lease financing obligations	(58)	(226)	(271)
Proceeds from sale of common stock, net	56,486	26,223	12,518
Issuance of common stock warrants	674	0	0
Proceeds from exercise of common stock warrants	0	0	2
Proceeds from issuance of common stock for employee stock purchase plan	1,793	1,489	1,295
Deferred offering costs	0	0	(152)
Tax withholdings related to net share settlements of restricted stock units	313	0	0
Proceeds from exercise of stock options	1,086	2,607	876
Net cash provided by financing activities	59,668	35,093	24,268
Net increase (decrease) in cash and cash equivalents	5,521	(1,247)	4,675
Effect of exchange rate changes on cash and cash equivalents	32	(26)	(42)
Cash and cash equivalents
Beginning of year	20,583	21,856	17,223
End of year	26,136	20,583	21,856
Supplemental disclosures
Cash paid for interest	4,416	4,071	2,844
Cash paid for taxes	154	217	69
Purchases of property and equipment, accrued but not paid	0	275	640
Rental instruments reclassified from inventory	1,023	801	772
Non-cash inventory exchange for services	0	28	112
Non-cash capital lease	0	0	48
Accrual of offering costs	$ 0	$ 0	$ 29

Description of the Business

Description of the Business	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business	Description of the Business NanoString Technologies, Inc. (the “Company”) was incorporated in the state of Delaware on June 20, 2003. The Company’s headquarters is located in Seattle, Washington. The Company’s technology enables direct detection, identification and quantification of individual target molecules in a biological sample by attaching a unique color coded fluorescent reporter to each target molecule of interest. The Company markets its proprietary nCounter Analysis System, consisting of instruments and consumables, including its Prosigna Breast Cancer Assay, to academic, government and biopharmaceutical and clinical laboratory customers. In addition, the Company collaborates with biopharma companies to develop companion diagnostic tests for various cancer therapies. The Company has incurred losses to date and expects to incur additional losses in the foreseeable future. The Company continues to devote the majority of its resources to the growth of its business in accordance with its business plan. The Company’s activities have been financed primarily through the sale of equity securities and incurrence of indebtedness, and to a lesser extent, capital leases and other borrowings. Public Offerings In May 2015, the Company entered into a sales agreement with a sales agent to sell shares of the Company’s common stock through an “at the market” equity offering program for up to $40.0 million in total sales proceeds. Pursuant to the sales agreement, the Company sold 1,331,539 and 960,400 shares during 2016 and 2015, respectively, for net proceeds of $26.1 million and $12.5 million , respectively. The Sales Agreement automatically terminated when the Company sold the maximum number of shares allowed under the agreement. In June 2017, the Company completed an underwritten public offering of 3,450,000 shares of common stock, including the exercise by the underwriter of an over-allotment option for 450,000 shares of common stock, for total gross proceeds of $57.8 million . After underwriter’s fees and commissions and other expenses of the offering, the Company’s aggregate net proceeds were approximately $56.5 million .

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Accounting Principles and Principles of Consolidation The consolidated financial statements and accompanying notes were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The accompanying consolidated financial statements reflect the accounts of the Company and its wholly-owned subsidiaries. Each of the subsidiaries operates as a sales and support office. The functional currency of each subsidiary is the U.S. dollar. All significant intercompany balances and transactions have been eliminated. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and that affect the reported amounts of revenue and expenditures during the reporting period. Actual results could differ from those estimates. Significant estimates inherent in the preparation of the accompanying consolidated financial statements include the estimation of the valuation of inventory, the fair value of the Company’s equity securities, the calculation of stock-based compensation and the estimated future cost of ongoing collaboration agreements, for which revenues are recognized on a proportional performance basis. Cash and Cash Equivalents The Company considers all highly-liquid investments with purchased maturities of three months or less to be cash equivalents. The Company’s cash equivalents consist principally of funds maintained in depository accounts. The Company invests its cash and cash equivalents with major financial institutions; at times these investments exceed federally insured limits. Investments The Company classifies its securities as available-for-sale, which are reported at estimated fair value with unrealized gains and losses included in accumulated other comprehensive loss in stockholders’ equity. Realized gains, realized losses and declines in the value of securities judged to be other-than-temporary, are included in other income (expense). The cost of investments for purposes of computing realized and unrealized gains and losses is based on the specific identification method. Amortization of premiums and accretion of discounts are included in other income (expense). Interest and dividends earned on all securities are included in other income (expense). Investments in securities with maturities of less than one year, or where management’s intent is to use the investments to fund current operations, or to make them available for current operations, are classified as short-term investments. If the estimated fair value of a security is below its carrying value, the Company evaluates whether it is more likely than not that it will sell the security before its anticipated recovery in market value and whether evidence indicating that the cost of the investment is recoverable within a reasonable period of time outweighs evidence to the contrary. The Company also evaluates whether or not it intends to sell the investment. If the impairment is considered to be other-than-temporary, the security is written down to its estimated fair value. In addition, the Company considers whether credit losses exist for any securities. A credit loss exists if the present value of cash flows expected to be collected is less than the amortized cost basis of the security. Other-than-temporary declines in estimated fair value and credit losses are charged against other income (expense). Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are stated at the amount management expects to collect from customers based on their outstanding invoices. Management reviews accounts receivable regularly to determine if any receivable will potentially be uncollectible and to estimate the amount of allowance for doubtful accounts necessary to reduce accounts receivable to its estimated net realizable value by analyzing the status of significant past due receivables. The allowance for doubtful accounts was $0.5 million as of December 31, 2017 , and $0.1 million as of December 31, 2016 , 2015 , and 2014 . Additions to the allowance were $0.4 million , $0 and $33,600 for the years ended December 31, 2017 , 2016 and 2015 , respectively. There were write-offs of uncollectible accounts of approximately $1,200 and $5,000 during the years ended December 31, 2017 and 2016 , respectively, and there were no write-offs during the year ended December 31, 2015 . Concentration of Credit Risks Financial instruments that potentially expose the Company to concentrations of credit risk consist principally of cash and cash equivalents, short-term investments and accounts receivable. Cash is invested in accordance with the Company’s investment policy, which includes guidelines intended to minimize and diversify credit risk. Most of the Company’s investments are not federally insured. The Company has credit risk related to the collectability of its accounts receivable. The Company performs initial and ongoing evaluations of its customers’ credit history or financial position and generally extends credit on account without collateral. The Company has not experienced any significant credit losses to date. The Company had two customers/collaborators, (1) Merck Sharp & Dohme Corp., a subsidiary of Merck& Co., Inc. (“Merck”), and (2) Medivation, Inc. and Astellas Pharma Inc., that represented 25% and 10% , respectively, of total revenue for the year ended December 31, 2017 and one customer/collaborator, Merck, that represented 13% of total revenue for the year ended December 31, 2016 . The Company had no customers or collaborators that represented more than 10% of total revenue for the year 2015 . The Company had no customers or collaborators that represented more than 10% of total accounts receivable as of December 31, 2017 and 2016 . The Company is also subject to supply chain risks related to the outsourcing of the manufacturing of its instruments to sole suppliers. Although there are a limited number of manufacturers for instruments of this type, the Company believes that other suppliers could provide similar products on comparable terms. A change in suppliers, however, could cause a delay in manufacturing and a possible loss of sales, which would adversely affect operating results. Fair value of financial instruments The recorded amounts of certain financial instruments, including cash and cash equivalents, accounts receivable, prepaid expenses and other assets, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. Investments that are classified as available-for-sale are recorded at fair value. The fair value for securities held is determined using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. The recorded amount of the Company’s long-term debt approximates fair value because the related interest rates approximate rates currently available to the Company. Inventory Inventory consists of finished goods, work in process, raw materials and certain component parts to be used in manufacturing or servicing the Company’s products. Inventory is stated at the lower of cost or net realizable value. Cost is determined using a standard cost system, whereby the standard costs are updated periodically to reflect current costs and market represents the lower of cost or market (replacement cost or estimated net realizable value). The Company’s policy is to establish inventory reserves when conditions exist that suggest that inventory may be in excess of anticipated demand, obsolete, slow moving or impaired. In the event that the Company identifies these conditions exist in its inventory, its carrying value is reduced to its net realizable value. Inventory reserves were $2.7 million as of December 31, 2017 and $2.2 million as of December 31, 2016 , 2015 , and 2014 . Additions to the reserves were $0.9 million , $0.8 million and $0.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Write-offs of inventory reserves for the years ended December 31, 2017 , 2016 and 2015 were $0.4 million , $0.7 million and $0.3 million , respectively. The Company outsources the manufacturing of its instruments to third-party contract manufacturers who manufacture them to certain specifications and source certain raw materials from sole source providers. Major delays in shipments, inferior quality, insufficient quantity or any combination of these or other factors may harm the Company’s business and results of operations. In addition, the inability of one or more of these suppliers to provide the Company with an adequate supply of its products or raw materials or the loss of one or more of these suppliers may cause a delay in the Company’s ability to fulfill orders while it obtains a replacement supplier and may harm the Company’s business and results of operations. Property and Equipment Property and equipment are recorded at cost, net of accumulated depreciation and amortization. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets. Manufacturing equipment is depreciated over five years , lease and loaner instruments are depreciated over one to five years , prototype systems are depreciated over two years , computer equipment is generally depreciated over three years , furniture and fixtures are depreciated over five years and leasehold improvements are amortized over the life of the related assets or the term of the lease, whichever is shorter. Expenditures for additions are capitalized and expenditures for maintenance and repairs are expensed as incurred. Gains and losses from the disposal of property and equipment are reflected in the consolidated statements of operations in the period of disposition. Leases and Leasehold Improvements Rent expense for leases that provide for scheduled rent increases during the lease term is recognized on a straight-line basis over the term of the related lease. Leasehold improvements that are funded by landlord incentives or allowances are recorded in property and equipment and as a component of deferred rent and are amortized as a reduction of rent expense over the term of the related lease. Impairment of Long-Lived Assets The Company recognizes impairment losses on long-lived assets when indicators of impairment are present and the anticipated undiscounted cash flows to be generated by those assets are less than the asset’s carrying values. The Company has not experienced any impairment losses on its long-lived assets during the periods presented. Segments Operating segments are defined as components of an entity for which separate financial information is available and evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the chief executive officer, who manages the operations and evaluates the financial performance on a total Company basis. The Company’s principal operations and decision-making functions are located at its corporate headquarters in the United States and the Company operates as a single reportable segment. Revenue Recognition The Company recognizes revenue when (1) persuasive evidence of an arrangement exists, (2) delivery has occurred or services have been rendered, (3) the price to the customer is fixed or determinable and (4) collectability is reasonably assured. The Company generates revenue from the sale of products and services. The Company’s products consist of its proprietary nCounter Analysis System and related consumables. Services consist of extended warranties and service fees for access to new technologies still under development or for assay processing. A delivered product or service is considered to be a separate unit of accounting when it has value to the customer on a stand-alone basis. Products or services have value on a stand-alone basis if they are sold separately by any vendor or the customer could resell the delivered product. Instruments, consumables and in vitro diagnostic kits are considered to be separate units of accounting as they are sold separately and revenue is recognized upon transfer of ownership, which is generally upon shipment. Instrument revenue related to installation and calibration services is recognized when services are rendered by the Company. Such services can also be provided by the Company’s distribution partners. For instruments sold for use primarily to run Prosigna assays for diagnostic purposes, training must be provided prior to instrument revenue recognition. Instrument revenue from leased instruments is recognized ratably over the lease term. Service revenue is recognized when earned, which is generally upon the rendering of the related services. Service agreements and service fees for assay processing are each considered separate units of accounting as they are sold separately. The Company offers service agreements on its nCounter Analysis System for periods ranging from 12 to 36 months after the end of the standard 12 -month warranty period. Service agreements are generally separately priced. Revenue from service agreements is deferred and recognized on a straight-line basis over the service period. For arrangements with multiple deliverables, the Company allocates the agreement consideration at the inception of the agreement to the deliverables based upon their relative selling prices. To date, selling prices have been established by reference to vendor specific objective evidence based on stand-alone sales transactions for each deliverable. Vendor specific objective evidence is considered to have been established when a substantial majority of individual sales transactions within the previous 12-month period fall within a reasonably narrow range, which the Company has defined to be plus or minus 15% of the median sales price of actual stand-alone sales transactions. The Company uses its best estimate of selling price for individual deliverables when vendor specific objective evidence or third-party evidence is unavailable. Allocated revenue is only recognized for each deliverable when the revenue recognition criteria have been met. The Company enters into collaborative agreements that may generate upfront fees with subsequent milestone payments that may be earned upon completion of development-related milestones. The Company is able to estimate the total cost of services under the arrangements and recognizes collaboration revenue using a proportional performance model. Costs incurred to date compared to total expected costs are used to determine proportional performance, as this is considered to be representative of the delivery of outputs under the arrangements. Revenue recognized at any point in time is limited to cash received and amounts contractually due. Changes in estimates of total expected costs are accounted for prospectively as a change in estimate. From period to period, collaboration revenue can fluctuate substantially based on the achievement of development-related milestones. Cost of Revenue Cost of revenue consists primarily of costs incurred in the production process, including costs of purchasing instruments from third-party contract manufacturers, consumable component materials and assembly labor and overhead, installation, warranty, service and packaging and delivery costs. In addition, cost of revenue includes royalty costs for licensed technologies included in the Company’s products, provisions for slow-moving and obsolete inventory and stock-based compensation expense. Cost of revenue for instruments and consumables is recognized in the period the related revenue is recognized. Shipping and handling costs incurred for product shipments are included in cost of revenue in the consolidated statements of operations. Reserve for Product Warranties The Company generally provides a one -year warranty on its nCounter Analysis Systems and establishes a reserve for future warranty costs based on historical product failure rates and actual warranty costs incurred. Warranty expense is recorded as a component of cost of revenue in the consolidated statements of operations. Research and Development Research and development expenses, consisting primarily of salaries and benefits, occupancy costs, laboratory supplies, clinical study costs, contracted services, consulting fees and related costs, are expensed as incurred. Selling, General and Administrative Selling expenses consist primarily of personnel related costs for sales and marketing, contracted services and service fees and are expensed as the related costs are incurred. Advertising costs are expensed as incurred and are included in sales and marketing expenses. Advertising costs totaled approximately $5.9 million , $5.3 million and $2.6 million during the years ended December 31, 2017 , 2016 and 2015 , respectively. General and administrative expenses consist primarily of personnel related costs for the Company’s finance, human resources, business development, legal, information technology and general management, as well as professional fees for legal, accounting, and other consulting services. General and administrative expenses are expensed as they are incurred. Income Taxes The Company accounts for income taxes under the liability method. Under the liability method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and income tax bases of assets and liabilities and are measured using the tax rates that will be in effect when the differences are expected to reverse. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized. The Company determines whether a tax position is more likely than not to be sustained upon examination based on the technical merits of the position. For tax positions meeting the more-likely-than-not threshold, the tax amount recognized in the financial statements is reduced by the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement with the relevant tax authority. Stock-Based Compensation The Company accounts for stock-based compensation under the fair value method. Stock-based compensation costs are based on option awards granted and vested based on their grant-date fair value, estimated using the Black-Scholes option pricing model. The Company uses the straight-line attribution method for recognizing compensation expense. Guarantees and Indemnifications In the normal course of business, the Company guarantees and/or indemnifies other parties, including vendors, lessors and parties to transactions with the Company, with respect to certain matters. The Company has agreed to hold the other parties harmless against losses arising from breach of representations or covenants, or out of intellectual property infringement or other claims made against certain parties. It is not possible to determine the maximum potential amount the Company could be required to pay under these indemnification agreements, since the Company has not had any prior indemnification claims, and each claim would be based upon the unique facts and circumstances of the claim and the particular provisions of each agreement. In the opinion of management, any such claims would not be expected to have a material adverse effect on the Company’s consolidated results of operations, financial condition or cash flows. The Company did not have any related liabilities recorded at December 31, 2017 and 2016 . Comprehensive Loss Comprehensive loss includes certain changes in equity that are excluded from net loss. Specifically, unrealized gains and losses on short-term investments are included in comprehensive loss. Recently Adopted Accounting Pronouncement In July 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) entitled “ASU 2015-11, Inventory – Simplifying the Measurement of Inventory.” The standard requires entities to measure inventory at the lower of cost and net realizable value. The Company adopted ASU 2015-11 in the first quarter of 2017 and adoption did not have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In March 2016, FASB issued “ASU 2016-09, Improvements to Employee Share-Based Payment Accounting” which amends Accounting Standard Codification Topic 718, “Compensation – Stock Compensation”. The standard includes provisions intended to simplify various aspects related to the accounting and presentation for stock-based payments in the financial statements, including the income tax effects of stock-based payments, minimum withholding requirements upon award settlement, and the method of calculating forfeitures in the recognition of stock compensation expense. The Company adopted ASU 2016-09 in the first quarter of 2017 and has elected to account for forfeitures as they occur to determine the amount of compensation cost to be recognized. The accounting policy election was adopted applying a modified retrospective approach, and did not have a material impact on the consolidated results of operations, financial condition, cash flows, or financial statement disclosures. Employee taxes paid for withheld shares are presented as a financing activity in the consolidated statements of cash flows, as required by the new standard, and was adopted retrospectively. Other provisions of ASU 2016-09 related to the accounting for the tax effects of stock-based payments have no impact on its consolidated results of operations, as the Company records a valuation allowance for deferred tax assets related to excess tax benefits from stock-based payment transactions. Recent Accounting Pronouncements As an “emerging growth company,” the Jumpstart Our Business Startups Act allows the Company to delay adoption of new or revised accounting pronouncements applicable to public companies until such pronouncements are made applicable to private companies. As a result, the Company's financial statements may not be comparable to the financial statements of issuers who are required to comply with the effective dates for new or revised accounting standards that are applicable to public companies. In May 2014, FASB issued “ASU 2014-09, Revenue from Contracts with Customers.” The standard requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to a customer. In March 2016, the FASB issued “ASU 2016-08, Principal vs Agent Considerations (Reporting Revenue Gross versus Net)” which clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued “ASU 2016-10, Identifying Performance Obligations and Licensing” which clarifies the implementation guidance on identifying performance obligations and the licensing implementation guidance. In May 2016, the FASB issued “ASU 2016-12, Narrow-Scope Improvements and Practical Expedients” which provides practical expedients for contract modifications and clarification on assessing the collectability criterion, presentation of sales taxes, measurement date for noncash consideration and completed contracts at transition. The Company has formed an implementation team and completed its preliminary assessment of the potential impact of implementing this new standard. The assessment included an analysis of the Company’s current portfolio of customer contracts and related costs, as well as a review of its historical accounting policies and practices to identify potential differences in applying the new standard. The Company has determined that its collaborative agreements fall within the scope of ASC 808, Collaborative Arrangements and intends to apply the principles of ASC 606 in the measurement and recognition of revenue. In addition, the Company has concluded that service contracts will no longer be accounted for under separate accounting guidance, but rather included as separate performance obligations within a contract subject to the new standard, which includes their inclusion in the determination and allocation of the aggregate transaction price based on their relative values, and recognition of revenue upon the delivery of the performance obligation. We have determined that such service contracts comprise two performance obligations, one related to an included right to an annual preventative maintenance service included within the agreements which will be recognized when performed or the right expires, and another related to the Company's stand-ready obligations under the service contracts will be recognized over the service period. The new standard also requires more extensive disclosures related to revenue recognition, particularly in quarterly financial statements. The Company adopted the new guidance on January 1, 2018 using the modified retrospective method of adoption, has evaluated the impact of the standard on all of its revenues, including those mentioned above, and concluded the adoption of the standard will not have a material impact on its consolidated results of operations, financial condition, or cash flows. In January 2016, FASB issued “ASU 2016-01, Financial Instruments: Overall.” The standard addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. The standard will become effective for the Company beginning January 1, 2018. The Company does not anticipate adoption of this standard will have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In February 2016, FASB issued “ASU 2016-02, Leases – Recognition and Measurement of Financial Assets and Financial Liabilities.” The standard requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition. The standard requires lessors to classify leases as either sales-type, finance or operating. A sales-type lease occurs if the lessor transfers all of the risks and rewards, as well as control of the underlying asset, to the lessee. If risks and rewards are conveyed without the transfer of control, the lease is treated as a financing lease. If the lessor does not convey risks and rewards or control, an operating lease results. The standard will become effective for the Company beginning January 1, 2019. The Company is currently assessing the impact adoption of this standard will have on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In June 2016, FASB issued “ASU 2016-13, Financial Instruments: Credit Losses”. The standard provides information about expected credit losses on financial instruments at each reporting date, and to change how other than temporary impairments on investments securities are recorded. The standard will become effective for the Company beginning on January 1, 2020 with early adoption permitted. The Company is currently assessing the impact adoption of this standard will have on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In August 2016, FASB issued “ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments”. The standard provides guidance on how certain cash receipts and cash payments are presented and classified in the statement of cash flows and is intended to reduce diversity in practice with respect to these items. The standard is applied using a retrospective transition method and will become effective for the Company on January 1, 2018. The Company does not anticipate adoption of this standard will have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In November 2016, FASB issued “ASU 2016-18, Statement of Cash Flows: Restricted Cash”. The standard requires companies to include amounts generally described as restricted cash and restricted cash equivalents, along with cash and cash equivalents, when reconciling the beginning-of-period and end-of-period amounts shown on the statement of cash flows. The standard was adopted by the Company on January 1, 2018. The Company does not anticipate adoption of this standard will have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In May 2017, FASB issued “ASU 2017-09, Compensation - Stock Compensation: Scope of Modification Accounting”. The standard clarifies which changes to the terms or conditions of a share-based payment award are required to be accounted for as modifications. The standard was adopted by the Company on January 1, 2018. The adoption of this standard did not have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures.

Short-term Investments

Short-term Investments	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Short-term Investments	Short-term Investments Short-term investments consisted of available-for-sale securities as follows (in thousands): Type of securities as of December 31, 2017 Amortized cost Gross unrealized gains Gross unrealized losses Fair value Corporate debt securities $ 35,567 $ — $ (53 ) $ 35,514 U.S. government-related debt securities 15,951 — (46 ) 15,905 Total available-for-sale securities $ 51,518 $ — $ (99 ) $ 51,419 Type of securities as of December 31, 2016 Amortized cost Gross unrealized gains Gross unrealized losses Fair value Corporate debt securities $ 36,198 $ 4 $ (42 ) $ 36,160 U.S. government-related debt securities 17,312 1 (20 ) 17,293 Total available-for-sale securities $ 53,510 $ 5 $ (62 ) $ 53,453 The fair values of available-for-sale securities by contractual maturity at December 31 were as follows (in thousands): 2017 2016 Maturing in one year or less $ 39,985 $ 46,310 Maturing in one to three years 11,434 7,143 Total available-for-sale securities $ 51,419 $ 53,453 The Company has both the intent and ability to sell its available-for-sale investments maturing greater than one year within 12 months from the balance sheet date and, accordingly, has classified these securities as current in the consolidated balance sheet. The following table summarizes investments that have been in a continuous unrealized loss position as of December 31, 2017 (in thousands). Less Than 12 Months 12 Months or Greater Total Fair value Gross unrealized losses Fair value Gross unrealized losses Fair value Gross unrealized losses Corporate debt securities $ 26,857 $ (53 ) $ — $ — $ 26,857 $ (53 ) U.S. government-related debt securities 8,911 (40 ) 3,994 (6 ) 12,905 (46 ) Total $ 35,768 $ (93 ) $ 3,994 $ (6 ) $ 39,762 $ (99 ) The Company invests in securities that are rated investment grade or better. The unrealized losses on investments as of December 31, 2017 and December 31, 2016 were primarily caused by interest rate increases. The Company reviews the individual securities in its portfolio to determine whether a decline in a security’s fair value below the amortized cost basis is other-than-temporary. The Company determined that as of December 31, 2017 , there were no investments in its portfolio that were other-than-temporarily impaired.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company establishes the fair value of its assets and liabilities using the price that would be received to sell an asset or paid to transfer a financial liability in an orderly transaction between market participants at the measurement date. A fair value hierarchy is used to measure fair value. The three levels of the fair value hierarchy are as follows: • Level 1 — Quoted prices in active markets for identical assets and liabilities. • Level 2 — Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. • Level 3 — Valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. The Company’s available-for-sale securities by level within the fair value hierarchy were as follows (in thousands): Type of securities as of December 31, 2017 Fair value measurement using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market fund $ 22,398 $ — $ — $ 22,398 Short-term investments: Corporate debt securities — 35,514 — 35,514 U.S. government-related debt securities — 15,905 — 15,905 Total $ 22,398 $ 51,419 $ — $ 73,817 Type of securities as of December 31, 2016 Fair value measurement using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market fund $ 16,715 $ — $ — $ 16,715 Short-term investments: Corporate debt securities — 36,160 — 36,160 U.S. government-related debt securities — 17,293 — 17,293 Total $ 16,715 $ 53,453 $ — $ 70,168

Inventory

Inventory	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventory	Inventory, Net Inventory consisted of the following at December 31 (in thousands): 2017 2016 Raw materials $ 5,743 $ 4,277 Work in process 4,845 4,046 Finished goods 9,469 5,489 Total inventory $ 20,057 $ 13,812 In 2017 and 2016 , the Company transferred into property, plant and equipment net amounts totaling $1.0 million and $0.8 million , respectively, of inventory that was leased, loaned, or assigned for internal use in the Company’s facilities.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment consisted of the following at December 31 (in thousands): Useful Life (Years) 2017 2016 Manufacturing equipment 5 $ 8,395 $ 6,445 Lease and loaner instruments 1 - 5 4,106 3,581 Prototype instruments 2 2,938 2,975 Computer equipment 3 2,067 1,592 Furniture and fixtures 5 1,670 1,642 Leasehold improvements Various 11,971 8,878 Construction in progress 158 1,861 Total property and equipment, gross 31,305 26,974 Less: Accumulated depreciation and amortization (17,248 ) (14,816 ) Total property and equipment, net $ 14,057 $ 12,158 Prototype instruments consist of nCounter instruments used in internal testing and other development activities. Accumulated depreciation on lease and loaner instruments was $1.9 million and $1.5 million at December 31, 2017 and 2016 , respectively. Depreciation and amortization expense related to property and equipment for the years ended December 31, 2017 , 2016 and 2015 totaled approximately $3.3 million , $2.9 million and $2.3 million , respectively.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt 2014 Term Loan Agreement In April 2014, the Company entered into a term loan agreement under which it may borrow up to $45.0 million , including an option to defer payment of a portion of the interest that would accrue on the borrowing under the term loan agreement. Upon initial closing, the Company borrowed $20.0 million , the proceeds of which were primarily used to repay the outstanding balance under the Company’s former credit facility plus a related $1.0 million end of term payment, a $0.3 million make-whole premium, and deferred interest. The Company incurred and recorded a total charge to interest expense of $1.4 million related to the repayment of the former credit facility, including a loss on extinguishment of debt of $0.6 million . In October 2014, the Company borrowed an additional $10.0 million under the term loan agreement. In October 2015, the Company amended the term loan agreement to, among other provisions, increase the maximum borrowing capacity to $60.0 million (excluding deferred interest), reduce the applicable interest rate from 12.5% to 12.0% , extend the interest-only period through March 2021, and extend the final maturity to March 2022. Under the amended agreement, borrowings accrue interest at 12.0% annually, payable quarterly, of which 3.0% can be deferred during the first six years of the term at the Company’s option and paid together with the principal at maturity. The Company has elected to exercise the option to defer a portion of the interest and has recorded $4.3 million of deferred interest through December 31, 2017 . In December 2015, the Company borrowed an additional $10.0 million under the terms of the amended agreement. In June 2016, the Company borrowed an additional $5.0 million . At December 31, 2016, the Company's option to borrow $15.0 million more under the amended term loan agreement expired. Total borrowings and deferred interest under the amended term loan agreement were $49.3 million and $47.8 million as of December 31, 2017 and 2016 , respectively. Under the amended term loan agreement, the Company may pay interest-only for the first seven years of the term and principal payments are due in four equal installments during the eighth year of the term. The Company has the option to prepay the term loan, in whole or part, at any time subject to payment of a redemption fee of up to 4% , which declines 1% annually, with no redemption fee payable if prepayment occurs after the fourth year of the loan. In addition, a facility fee equal to 2.0% of the amount borrowed plus any accrued interest is payable at the end of the term or when the loan is repaid in full. A long-term liability of $1.1 million is being accreted using the effective interest method for the facility fee over the term of the loan agreement. Obligations under the term loan agreement are collateralized by substantially all of the Company’s assets. The term loan agreement contains customary conditions to borrowings, events of default and negative covenants, including covenants that could limit the Company’s ability to, among other things, incur additional indebtedness, liens or other encumbrances, make dividends or other distributions; buy, sell or transfer assets; engage in any new line of business; and enter into certain transactions with affiliates. The term loan agreement also includes a $2.0 million minimum liquidity covenant and revenue-based financial covenants, which was $85.0 million for 2017 with annual increases of $15.0 million for each subsequent fiscal year thereafter. If the Company’s actual revenues are below the minimum annual revenue requirement for any given year, it may avoid a related default by generating proceeds from an equity or subordinated debt issuance equal to the shortfall between its actual revenues and the minimum revenue requirement. The Company was in compliance with its financial covenants as of December 31, 2017 . The Company incurred $6.2 million , $5.7 million and $4.0 million of interest expense under the term loan agreement for the years ended December 31, 2017 , 2016 and 2015 , respectively. Lease Financing Obligations The Company entered into agreements to lease certain hardware, software and capitalized installation costs, the longest of which expired in June 2017. Ownership of the leased property transferred to the Company at the end of the lease term. The fair value at lease inception was recorded in property, plant and equipment and depreciated over the shorter of the useful life of the assets or the lease term. A total cost of $0.7 million for leased property is included in property and equipment at December 31, 2017 and 2016 , with accumulated depreciation of $0.7 million and $0.5 million at December 31, 2017 and 2016 , respectively. Long-term debt and lease financing obligations consisted of the following at December 31 (in thousands): 2017 2016 Term loans payable $ 49,315 $ 47,844 Lease financing obligations — 58 Total long-term debt and lease financing obligations 49,315 47,902 Unamortized debt issuance costs (384 ) (478 ) Current portion of lease financing obligations — (58 ) Long-term debt and lease financing obligations, net of debt issuance costs and current portion $ 48,931 $ 47,366 Scheduled future payments of principal for outstanding debt and lease financing obligations were as follows at December 31: 2018 $ — 2019 — 2020 — 2021 36,987 2022 12,328 $ 49,315

Collaboration Agreements

Collaboration Agreements	12 Months Ended
	Dec. 31, 2017
Deferred Revenue Disclosure [Abstract]
Collaboration Agreements	Collaboration Agreements The Company evaluates the statement of operations classification of payments between the participants in each of its collaboration agreements at inception based on the nature of the arrangement, the nature of its business operations and the contractual terms of the arrangement. The Company has determined that amounts to be received from collaborators in connection with the collaboration agreements entered into through December 31, 2017 are related to revenue generating activities. The Company uses a contingency-adjusted proportional performance model to recognize revenue over the Company’s performance period for each collaboration agreement that includes upfront and/or milestone-based payments. Costs incurred to date compared to total expected costs are used to determine proportional performance, as this is considered to be representative of the delivery of outputs under the arrangement. Revenue recognized at any point in time is a factor of and limited to cash received and amounts contractually due. Changes in estimates of total expected costs are accounted for prospectively. The Company recognizes revenue from collaboration agreements that do not include upfront and/or milestone-based payments when earned, which is generally in the same period related costs are incurred. Amounts due to collaboration partners are recognized when the related activities have occurred and are classified in the statement of operations, generally as research and development expense, based on the nature of the related activities. Lam Research Corporation In August 2017, the Company entered into a collaboration agreement with Lam Research Corporation (“Lam”) with respect to the development and commercialization of the Hyb & Seq sequencing platform and related assays. Pursuant to the terms of the collaboration agreement, Lam will contribute up to an aggregate of $50.0 million , payable quarterly, based on allowable development costs. Lam is eligible to receive certain single-digit percentage royalty payments from the Company on net sales of certain products and technologies developed under the collaboration agreement. The maximum amount of royalties payable to Lam will be capped at an amount up to three times the amount of development funding actually provided by Lam. The Company will retain exclusive rights to obtain regulatory approval, manufacture and commercialize the Hyb & Seq products. Lam will participate in development through a joint steering committee. The Company will reimburse Lam for the cost of up to 10 full-time Lam employees each year in accordance with the product development plan. In connection with the execution of the collaboration agreement, the Company issued Lam a warrant to purchase up to 1.0 million shares of the Company’s common stock with the number of underlying shares exercisable at any time proportionate to the amount of the $50.0 million commitment that has been provided by Lam. The exercise price of the warrant is $16.75 per share, and it will expire on the seventh anniversary of the issuance date. The warrant was determined to have a fair value of $6.7 million upon issuance, and such amount will be recorded as additional paid in capital proportionately from the quarterly collaboration payments made by Lam. The Company recognized collaboration revenue of $3.7 million for the year ended December 31, 2017 . The Company received development funding of $13.4 million related to the Lam collaboration for the year ended December 31, 2017 , of which $8.3 million is included in customer deposits in the consolidated balance sheet as of December 31, 2017 representing amounts received in advance. Through December 31, 2017 , no amounts are due or have been paid by the Company to Lam for services provided by Lam employees under the terms of the agreement. During 2017, Lam did not exercise any warrants. Celgene Corporation In March 2014, the Company entered into a collaboration agreement with Celgene Corporation (“Celgene”) to develop, seek regulatory approval for, and commercialize a companion diagnostic using the nCounter Analysis System to identify a subset of patients with Diffuse Large B-Cell Lymphoma. Pursuant to the Company's agreement as amended in February 2018, the Company is eligible to receive payments from Celgene totaling up to $27.3 million , of which $5.8 million was received as an upfront payment upon delivery of certain information to Celgene and $21.5 million is for development funding and potential success-based development and regulatory milestones. There have been several amendments to the collaboration agreement and in return the Company has received additional payments totaling $2.1 million . The Company will retain all commercial rights to the diagnostic test developed under this collaboration, subject to certain backup rights granted to Celgene to commercialize the diagnostic test in a particular country if the Company elects to cease distribution or elects not to distribute the diagnostic in such country. Assuming success in the clinical trial process, and subject to regulatory approval, the Company will market and sell the diagnostic assay. The Company achieved and was paid for milestones totaling $6.0 million during 2014. The process of successfully developing a product candidate, obtaining regulatory approval and ultimately commercializing a product candidate is highly uncertain and the attainment of any additional milestones is therefore uncertain and difficult to predict. In addition, certain milestones are outside the Company’s control and are dependent on the performance of Celgene and the outcome of a clinical trial and related regulatory processes. Accordingly, the Company is not able to reasonably estimate when, if at all, any additional milestone payments may be payable to the Company by Celgene. See Note 17. Subsequent Events for an update to this collaboration agreement. The Company recognized collaboration revenue related to the Celgene agreement of $0.2 million , $3.2 million and $2.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. At December 31, 2017 , the Company had recorded $5.4 million of deferred revenue related to the Celgene collaboration, of which $3.7 million is estimated to be recognizable as revenue within one year. Merck & Co., Inc. In May 2015, the Company entered into a clinical research collaboration agreement with Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc. (“Merck”), to develop an assay intended to optimize immune-related gene expression signatures and evaluate the potential to predict benefit from Merck’s anti-PD-1 therapy, KEYTRUDA. Under the terms of the collaboration agreement, the Company received $3.9 million in payments during 2015. In connection with the execution of the development collaboration agreement, the Company and Merck terminated the May 2015 clinical research collaboration and moved all remaining activities under the related work plan to the new development collaboration agreement. In February 2016, the Company expanded its collaboration with Merck by entering into a new development collaboration agreement to clinically develop, seek regulatory approval for, and commercialize a companion diagnostic test to predict response to KEYTRUDA in multiple tumor types. During 2016, the Company received $12.0 million upfront as a technology access fee and $8.5 million of preclinical milestone payments. In October 2017, Merck notified the Company of its decision not to pursue regulatory approval of the companion diagnostic test for KEYTRUDA. As a result, the scope of the collaboration was significantly reduced, and activities respecting this collaboration are expected to be materially concluded in 2018. The Company recognized collaboration revenue related to the Merck agreement of $27.0 million , $8.6 million , and $3.7 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. As of December 31, 2017 , the Company had recorded $1.1 million of deferred revenue related to the Merck collaboration, $1.0 million of which is estimated to be recognized as revenue within one year. The Company received development funding of $6.8 million , $8.7 million , and $3.9 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Medivation, Inc. and Astellas Pharma, Inc. In January 2016, the Company entered into a collaboration agreement with Medivation, Inc. ("Medivation") and Astellas Pharma Inc. (“Astellas”) to pursue the translation of a novel gene expression signature algorithm discovered by Medivation into a companion diagnostic assay using the nCounter Analysis System. In September 2016, Medivation was acquired by Pfizer, Inc. (“Pfizer”) and became a wholly owned subsidiary of Pfizer. In May 2017, the Company received notification from Pfizer and Astellas terminating the collaboration agreement as a result of a decision to discontinue the related clinical trial. The Company recognized collaboration revenue of $11.5 million and $4.8 million related to the Medivation/Astellas agreement for the years ended December 31, 2017 and 2016 , respectively, including the favorable impact of a $1.0 million termination penalty during 2017. The Company achieved and was paid for milestones totaling $6.0 million during 2016. The Company received development funding of $0.9 million and $2.4 million for the years ended December 31, 2017 and 2016 , respectively.

Common Stock and Preferred Stoc

Common Stock and Preferred Stock	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Common Stock and Preferred Stock	Common Stock and Preferred Stock Common Stock Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of other classes of stock outstanding. Preferred Stock Pursuant to the amended and restated certificate of incorporation filed by the Company immediately prior to the completion of its initial public offering, the Company’s board of directors is authorized to issue up to 15,000,000 shares of preferred stock in one or more series and to fix the rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, redemption rights, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock. The issuance of preferred stock could adversely affect the voting power of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing change in the Company’s control or other corporate action. As of December 31, 2017 , no shares of preferred stock were issued or outstanding, and the board of directors has not authorized or designated any rights, preferences, privileges and restrictions for any class of preferred stock. Warrants Prior to the Company’s initial public offering, warrants to purchase preferred stock were issued related to certain financing transactions. All preferred stock warrants were converted into warrants to purchase common stock upon the effectiveness of the initial public offering. As of December 31, 2017 there were 355,585 common stock warrants outstanding with a weighted average exercise price of $10.96 per share and expiration dates ranging from 2018 to 2024 .

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation	Stock-based Compensation 2004 Stock Option Plan and 2013 Equity Incentive Plan The Company’s 2004 Stock Option Plan and 2013 Equity Incentive Plan (the “Plans”) authorize the grant of options, restricted stock units (“RSUs”) and other equity awards to employees, directors and consultants. As of December 31, 2017 , there were 7,501,801 shares authorized under the Plans. All options granted have a ten -year term and generally vest and become exercisable over four years of continued employment or service as defined in each option agreement. The Board of Directors determines the option exercise price and may designate stock options granted as either incentive or nonstatutory stock options. The Company generally grants stock options to employees with exercise prices equal to the estimated fair value of the Company’s common stock on the date of grant. Stock Option Activity A summary of the Company’s stock option activity under the Plans is as follows: Shares Weighted- average exercise price per share Weighted- average remaining contractual term (in years) Aggregate intrinsic value (in thousands) Outstanding at January 1,2017 4,721,941 $ 12.00 7.41 $ 48,670 Granted 1,180,086 17.90 Canceled and forfeited (478,078 ) 15.90 Exercised (227,696 ) 4.78 Outstanding at December 31, 2017 5,196,253 $ 13.32 6.98 $ 3,861 December 31, 2017: Options vested and expected to vest 4,792,694 $ 13.07 6.84 $ 3,861 Options exercisable 3,437,421 $ 11.90 6.19 $ 3,861 The weighted-average grant-date fair value per share of options granted with exercise prices equal to the market price on the date of the grant were $9.08 , $6.79 , and $7.07 for the years ended December 31, 2017 , 2016 , and 2015 , respectively. The aggregate intrinsic value in the table above is calculated as the difference between the exercise price of the underlying options and the quoted price of the Company’s common stock for all options that were in-the-money at December 31, 2017 . The aggregate intrinsic value of options exercised was $2.4 million during 2017 , $5.0 million during 2016 , and $2.1 million during 2015 , determined as of the option exercise date. The fair value of options vested was $8.9 million , $6.8 million , and $6.5 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. The following table summarizes information about the Company’s stock options outstanding at December 31, 2017 : Outstanding Exercisable Exercise Price Number of Shares Weighted- Average Remaining Contractual Life in Years Number of Shares Weighted- Average Remaining Contractual Life in Years $1.92 431,345 4.21 431,345 4.21 $2.24 – $6.72 494,155 3.87 494,155 3.87 $7.47 – $12.56 480,694 6.76 384,717 6.28 $12.77 674,356 7.06 488,124 7.04 $12.94 577,212 8.05 276,718 7.99 $13.01 – $14.95 360,230 7.62 241,553 7.42 $14.99 – $17.50 531,282 8.27 218,634 7.36 $17.89 – $18.90 1,346,556 7.63 806,525 6.66 $19.09 – $22.71 300,423 8.22 95,650 7.33 5,196,253 3,437,421 In January 2014, the compensation committee of the Company's board of directors delegated authority to a committee of the Company's officers to make new-hire option grants, and in October 2015 further delegated the authority for the committee to make merit option grants, to non-officer employees. The authority of this committee is limited by a charter approved by the compensation committee of the Company's board of directors, the 2013 equity incentive plan and Delaware law. During 2017, the Company became aware of certain new higher option grants that had not been done in accordance with the committee’s charter. The Company took appropriate steps to fix these issues, which included ratification of a number of option grants, adjustments to the grant dates and/or grant prices, and in some cases, cancellation of certain grants. In the aggregate, the Company modified approximately 265,000 stock option awards to correct the exercise price and grant date for these awards which affected 109 employees of the Company, and as a result, during the year ended December 31, 2017, the Company recorded approximately $50,000 of incremental stock based compensation cost resulting from the modifications to these stock awards. Restricted Stock Unit (RSU) Activity A summary of RSU activity under the Plans is as follows: Non-vested RSUs Share Equivalent Weighted-Average Grant Date Fair Value Non-vested at January 1, 2017 163,602 $ 15.70 Changes during the year: Granted 603,493 10.73 Vested (66,956 ) 15.77 Forfeited (38,432 ) 17.20 Non-vested at December 31, 2017 661,707 $ 11.07 The fair value of the RSUs is determined based on the closing price of the Company’s common stock on the date of grant. The fair value of vested RSUs was $1.1 million and $64,000 for the years ended December 31, 2017 and 2016 . There were no vested RSUs for the year ended December 31, 2015 . Stock-based compensation The following table sets forth stock-based compensation expense related to stock-based arrangements under the Plans for the years ended December 31 as follows (in thousands): 2017 2016 2015 Cost of revenue $ 719 $ 548 $ 471 Research and development 2,853 2,046 1,453 Selling, general and administrative 7,047 5,602 3,919 Total stock-based compensation expense $ 10,619 $ 8,196 $ 5,843 As of December 31, 2017 , total unrecognized stock-based compensation cost related to non-vested options was $19.2 million . This cost will be recognized on a straight-line basis over the weighted-average remaining service period of 2.35 years . The Company utilizes newly issued shares to satisfy option exercises. No tax benefit was recognized related to stock-based compensation cost since the Company has not reported taxable income to date and has established a full valuation allowance to offset all of the potential tax benefits associated with its deferred tax assets. Valuation assumptions The fair value of each employee option grant as of December 31 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions: 2017 2016 2015 Risk-free interest rates 1.40% - 2.26% 1.18% - 2.12% 1.37% - 1.97% Expected term (years) 5.50 - 6.25 5.50 - 6.50 6.25 Expected dividend yield — — — Expected volatility 53.9% - 58.0% 47.0% 57.0% The risk-free interest rates are based on the implied yield currently available in U.S. Treasury securities at maturity with an equivalent term. For purposes of determining the expected term of the awards in the absence of sufficient historical data relating to stock-option exercises, the Company applies a simplified approach in which the expected term of an award is presumed to be the mid-point between the vesting date and the expiration date of the award. The Company has not declared or paid any dividends and does not currently expect to do so in the foreseeable future. The Company based its expected volatility on the historical volatility of similar companies whose share prices are publicly available, as management does not believe that the limited history of the Company’s measureable stock price volatility is representative of future expectations. Employee Stock Purchase Plan The Company’s 2013 Employee Stock Purchase Plan (“ESPP”) provides eligible employees with an opportunity to purchase common stock from the Company and to pay for their purchases through payroll deductions. The ESPP has overlapping offering periods of approximately 12 months in length. The offering periods generally start with the first trading day on or after March 1 and September 1 of each year and end on the first trading day on or after March 1 and September 1 of the following year, approximately 12 months later. Within each offering period, shares are purchased each six months on an exercise date. An employee electing to participate in the ESPP (a “participant”) will be granted an option at the start of the offering period to purchase shares with contributions in any whole percentage ranging from 0% to 10% (or greater or lesser percentages or dollar amounts that the administrator determines) of the participant’s eligible compensation. The participant’s contributions will be accumulated and then used to purchase the Company’s shares on each exercise date. The purchase price on the exercise date will be 85% of the fair market value of the lesser of the Company’s share price on either the first trading day of the offering period or on the exercise date. During 2017 , 2016 , and 2015 , shares issued under the ESPP were 138,972 , 139,195 , and 136,078 , respectively. The Company recorded share-based compensation expense for shares issued from the ESPP of $0.8 million , $0.8 million , and $0.4 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. A total of 825,442 shares of common stock have been reserved for issuance under the ESPP, of which 269,811 shares were available for issuance as of December 31, 2017 .

Defined Contribution Retirement

Defined Contribution Retirement Plan	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Defined Contribution Retirement Plan	Defined Contribution Retirement Plan The Company maintains a 401(k) defined contribution retirement plan covering substantially all of its employees. The plan provides for matching and discretionary contributions by the Company. Contributions were $1.2 million , $0.9 million , and $0.5 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Loss before income taxes for the years ended December 31 consisted of the following (in thousands): 2017 2016 2015 Domestic $ (44,324 ) $ (47,562 ) $ (46,065 ) Foreign 966 589 650 Loss before income taxes $ (43,358 ) $ (46,973 ) $ (45,415 ) Significant components of our provision for income taxes for the years ended December 31 are as follows (in thousands): 2017 2016 2015 Current: Domestic $ — $ — $ — Foreign 204 116 166 Total provision for income taxes $ 204 $ 116 $ 166 The Tax Cuts and Jobs Act, or the Act, was enacted on December 22, 2017, which reduced the U.S. federal corporate tax rate from 35% to 21%, among other changes. The Company’s accounting for the elements of the Act is complete and resulted in a $37.7 million reduction in its net deferred tax assets as of December 31, 2017 to reflect the new statutory rate. The rate adjustment to the deferred tax assets was fully offset by a decrease in the valuation allowance, resulting in no rate impact to the Company. A reconciliation of the federal statutory income tax rate to the effective income tax rate for the years ended December 31 are as follows (in thousands): 2017 2016 2015 Income tax provision at statutory rate $ (15,076 ) $ (16,010 ) $ (15,662 ) Tax on repatriated foreign earnings and other nondeductible items 179 135 401 Change in tax credits (2,361 ) (1,449 ) (792 ) Change in valuation allowance (19,792 ) 17,824 16,706 Change in tax rate 37,690 — — Foreign tax and other (436 ) (384 ) (487 ) Total provision for income taxes $ 204 $ 116 $ 166 Net operating loss (“NOL”) carryforwards created by excess tax benefits from the exercise of non-qualified stock options are not recorded as deferred income tax assets. To the extent such NOL carryforwards are utilized, the benefit realized will increase stockholders’ equity. At December 31, 2017 , for income tax return purposes the Company has gross federal and state NOL carryforwards totaling $232.8 million and tax credit carryforwards of $7.0 million . These carryforwards may be subject to limitations under the Internal Revenue Code and applicable state tax law. If not utilized, a portion of the carryforwards will begin to expire in 2025 through 2038 . The Company does not expect to utilize any of its net operating loss and tax credit carryforwards in the near term. The Company may have already experienced one or more ownership changes. Depending on the timing of any future utilization of its carryforwards, the Company may be limited as to the amount that can be utilized each year as a result of such previous ownership changes. However, the Company does not believe such limitations will cause its carryforwards to expire unutilized. Future changes in the Company’s stock ownership as well as other changes that may be outside the Company’s control could potentially result in further limitations on the Company’s ability to utilize its net operating loss and tax credit carryforwards. The effect of temporary differences and carryforwards that give rise to deferred tax assets for the years ended December 31 were as follows (in thousands): 2017 2016 Net operating loss carryforwards $ 49,662 $ 70,694 Research and development tax credit carryforwards 6,505 4,572 Foreign tax credit carryforwards 448 — Stock-based compensation 5,664 5,360 Other 6,382 7,827 Total deferred tax assets 68,661 88,453 Less: Valuation allowance (68,661 ) (88,453 ) Net deferred tax assets $ — $ — The Company has recorded a full valuation allowance related to its deferred tax assets due to the uncertainty of the ultimate realization of the future benefits from those assets. The table below summarizes changes in the deferred tax asset valuation allowance for the years ended December 31 (in thousands): 2017 2016 2015 Balance at beginning of year $ 88,453 $ 70,629 $ 53,923 Charged to costs and expenses 17,898 17,824 16,706 Impact of change in tax rate (37,690 ) — — Balance at end of year $ 68,661 $ 88,453 $ 70,629 The total balance of unrecognized gross tax benefits for the years ended December 31, resulting from research and development tax credits claimed on the Company’s annual tax return was as follows (in thousands): 2017 2016 2015 Unrecognized tax benefits at beginning of year $ 1,524 $ 1,041 $ 777 Additions based on current year tax positions 644 483 264 Unrecognized tax benefits at end of year $ 2,168 $ 1,524 $ 1,041 The Company classifies applicable interest and penalties on amounts due to tax authorities as a component of the provision for income taxes. The amount of accrued interest and penalties recorded in 2017 , 2016 or 2015 was not significant. The Company does not anticipate that the amount of its existing unrecognized tax benefits will significantly increase or decrease within the next 12 months. Due to the presence of net operating loss carryforwards in most jurisdictions, the Company’s tax years remain open for examination by U.S. taxing authorities back to 2004 .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company is obligated to make future minimum payments under three operating leases for 106,740 square feet of space used for general office, laboratory, manufacturing, operations, and research and development purposes primarily in Seattle. The leases expire beginning in 2018 to 2026 and include options to renew at the then current fair market rental for each of the facilities. The lease agreements contain rent abatement periods, scheduled rent increases and provide for tenant improvement allowances. Accordingly, the Company has recorded a deferred rent liability of $8.7 million and $7.5 million as of December 31, 2017 and 2016 , respectively. This deferred rent liability is amortized over the term of the related lease. Rent expense totaled approximately $4.8 million , $3.8 million and $3.2 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Future minimum lease payments under noncancelable operating leases as of December 31, 2017 were as follows (in thousands): 2018 $ 5,316 2019 5,307 2020 5,418 2021 5,551 2022 5,708 Thereafter 19,327 $ 46,627 Purchase Commitments The Company has non-cancellable purchase obligations totaling $4.4 million at December 31, 2017 related to binding commitments to purchase inventory and other research and development items. Contingencies From time to time, the Company may become involved in litigation relating to claims arising from the ordinary course of business. Management believes that there are no claims or actions pending against the Company currently, the ultimate disposition of which would have a material adverse effect on the Company’s consolidated results of operation, financial condition or cash flows.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding. Outstanding stock options, warrants and preferred stock have not been included in the calculation of diluted net loss per share because to do so would be anti-dilutive. Accordingly, the numerator and the denominator used in computing both basic and diluted net loss per share for each period are the same. The following outstanding options, restricted stock units and warrants as of December 31 were excluded from the computation of diluted net loss per share for the periods presented because their effect would have been anti-dilutive (in thousands): 2017 2016 2015 Options to purchase common stock 5,335 4,711 4,069 Restricted stock units 313 115 — Common stock warrants 317 491 572

Information about Geographic Ar

Information about Geographic Areas	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Information about Geographic Areas	Information about Geographic Areas The following table is based on the geographic location of distributors or end users who purchased products and services and collaborators. For sales to distributors, their geographic location may be different from the geographic locations of the ultimate end user. Revenue by geography as of December 31 was as follows (in thousands): 2017 2016 2015 Americas $ 86,099 $ 60,330 $ 41,265 Europe & Middle East 21,791 18,497 14,807 Asia Pacific 7,015 7,662 6,595 Total revenue $ 114,905 $ 86,489 $ 62,667 Total revenue in the United States was $84.0 million , $58.0 million and $37.9 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The Company’s assets are primarily located in the United States and not allocated to any specific geographic region. Substantially all of the Company’s long-lived assets are located in the United States.

Condensed Quarterly Financial D

Condensed Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Condensed Quarterly Financial Data (unaudited)	Condensed Quarterly Financial Data (unaudited) The following table contains selected unaudited financial data for each quarter of 2017 and 2016 . The unaudited information should be read in conjunction with the Company’s financial statements and related notes included elsewhere in this report. The Company believes that the following unaudited information reflects all normal recurring adjustments necessary for a fair statement of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period. Three months ended March 31, June 30, September 30, December 31, (in thousands, except per share data) 2017 Total revenue $ 18,063 $ 34,592 $ 27,016 $ 35,234 Net loss $ (18,852 ) $ (4,555 ) $ (11,404 ) $ (8,751 ) Net loss per share – basic and diluted $ (0.87 ) $ (0.20 ) $ (0.45 ) $ (0.34 ) 2016 Total revenue $ 14,697 $ 22,627 $ 23,933 $ 25,232 Net loss $ (14,603 ) $ (10,805 ) $ (10,088 ) $ (11,593 ) Net loss per share – basic and diluted $ (0.74 ) $ (0.55 ) $ (0.51 ) $ (0.55 )

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events In January 2018, the Company entered into a sales agreement with a sales agent to sell shares of the Company's common stock through an "at the market" equity offering program for up to $40.0 million in gross cash proceeds. The sales agreement allows the Company to set the parameters for the sale of shares, including the number of shares to be issued, the time period during which sales are requested to be made, limits on the number of shares that may be sold in any one trading day and a minimum price below which sales may not be made. Under the terms of the Sales Agreement, commission expenses to the sales agent will be 3% of the gross sales price per share sold through the sales agent. The Sales Agreement shall automatically terminate upon the issuance and sale of placement shares equaling sales proceeds of $40.0 million and may be terminated earlier by either the Company or the sales agent upon five days’ notice. In January 2018, the Company, as borrower, entered into a $15.0 million secured revolving loan facility, with availability subject to a borrowing base consisting of eligible accounts receivable. The agreement matures in January 2021, at which time the outstanding principal will become due and payable. Interest on borrowings is payable monthly and accrues at a yearly rate equal to the greater of the prime rate, as reported in the Wall Street Journal, plus 0.50% or 4.75% . During an event of default amounts drawn accrue interest at a yearly rate equal to 8.75% . Obligations under the agreement are collateralized by substantially all of the Company’s assets. In February 2018, the Company and Celgene entered into an amendment to their collaboration agreement in which Celgene agreed to provide the Company additional funding for work intended to enable a subtype and prognostic indication for the test being developed under the agreement for Celgene’s drug REVLIMID. In addition, the amendment provides an additional milestone payment to the Company payable upon achievement of certain regulatory activities and timelines. In connection with this amendment, the Company agreed to remove the right to receive payments from Celgene in the event commercial sales of the companion diagnostic test do not exceed certain pre-specified minimum annual revenues during the first three years following regulatory approval. In addition, the amendment allows Celgene, at its election, to use trial samples with additional technologies for companion diagnostics.

Significant Accounting Polici26

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Accounting Principles and Principles of Consolidation	The consolidated financial statements and accompanying notes were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The accompanying consolidated financial statements reflect the accounts of the Company and its wholly-owned subsidiaries. Each of the subsidiaries operates as a sales and support office. The functional currency of each subsidiary is the U.S. dollar. All significant intercompany balances and transactions have been eliminated.
Use of Estimates	The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and that affect the reported amounts of revenue and expenditures during the reporting period. Actual results could differ from those estimates. Significant estimates inherent in the preparation of the accompanying consolidated financial statements include the estimation of the valuation of inventory, the fair value of the Company’s equity securities, the calculation of stock-based compensation and the estimated future cost of ongoing collaboration agreements, for which revenues are recognized on a proportional performance basis.
Cash and Cash Equivalents	The Company considers all highly-liquid investments with purchased maturities of three months or less to be cash equivalents. The Company’s cash equivalents consist principally of funds maintained in depository accounts. The Company invests its cash and cash equivalents with major financial institutions; at times these investments exceed federally insured limits.
Investments	The Company classifies its securities as available-for-sale, which are reported at estimated fair value with unrealized gains and losses included in accumulated other comprehensive loss in stockholders’ equity. Realized gains, realized losses and declines in the value of securities judged to be other-than-temporary, are included in other income (expense). The cost of investments for purposes of computing realized and unrealized gains and losses is based on the specific identification method. Amortization of premiums and accretion of discounts are included in other income (expense). Interest and dividends earned on all securities are included in other income (expense). Investments in securities with maturities of less than one year, or where management’s intent is to use the investments to fund current operations, or to make them available for current operations, are classified as short-term investments. If the estimated fair value of a security is below its carrying value, the Company evaluates whether it is more likely than not that it will sell the security before its anticipated recovery in market value and whether evidence indicating that the cost of the investment is recoverable within a reasonable period of time outweighs evidence to the contrary. The Company also evaluates whether or not it intends to sell the investment. If the impairment is considered to be other-than-temporary, the security is written down to its estimated fair value. In addition, the Company considers whether credit losses exist for any securities. A credit loss exists if the present value of cash flows expected to be collected is less than the amortized cost basis of the security. Other-than-temporary declines in estimated fair value and credit losses are charged against other income (expense).
Accounts Receivable and Allowance for Doubtful Accounts	Accounts receivable are stated at the amount management expects to collect from customers based on their outstanding invoices. Management reviews accounts receivable regularly to determine if any receivable will potentially be uncollectible and to estimate the amount of allowance for doubtful accounts necessary to reduce accounts receivable to its estimated net realizable value by analyzing the status of significant past due receivables.
Concentration of Credit Risks	Financial instruments that potentially expose the Company to concentrations of credit risk consist principally of cash and cash equivalents, short-term investments and accounts receivable. Cash is invested in accordance with the Company’s investment policy, which includes guidelines intended to minimize and diversify credit risk. Most of the Company’s investments are not federally insured. The Company has credit risk related to the collectability of its accounts receivable. The Company performs initial and ongoing evaluations of its customers’ credit history or financial position and generally extends credit on account without collateral. The Company is also subject to supply chain risks related to the outsourcing of the manufacturing of its instruments to sole suppliers. Although there are a limited number of manufacturers for instruments of this type, the Company believes that other suppliers could provide similar products on comparable terms. A change in suppliers, however, could cause a delay in manufacturing and a possible loss of sales, which would adversely affect operating results.
Fair value of financial instruments	The recorded amounts of certain financial instruments, including cash and cash equivalents, accounts receivable, prepaid expenses and other assets, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. Investments that are classified as available-for-sale are recorded at fair value. The fair value for securities held is determined using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. The recorded amount of the Company’s long-term debt approximates fair value because the related interest rates approximate rates currently available to the Company.
Inventory	The Company outsources the manufacturing of its instruments to third-party contract manufacturers who manufacture them to certain specifications and source certain raw materials from sole source providers. Major delays in shipments, inferior quality, insufficient quantity or any combination of these or other factors may harm the Company’s business and results of operations. In addition, the inability of one or more of these suppliers to provide the Company with an adequate supply of its products or raw materials or the loss of one or more of these suppliers may cause a delay in the Company’s ability to fulfill orders while it obtains a replacement supplier and may harm the Company’s business and results of operations. Inventory consists of finished goods, work in process, raw materials and certain component parts to be used in manufacturing or servicing the Company’s products. Inventory is stated at the lower of cost or net realizable value. Cost is determined using a standard cost system, whereby the standard costs are updated periodically to reflect current costs and market represents the lower of cost or market (replacement cost or estimated net realizable value). The Company’s policy is to establish inventory reserves when conditions exist that suggest that inventory may be in excess of anticipated demand, obsolete, slow moving or impaired. In the event that the Company identifies these conditions exist in its inventory, its carrying value is reduced to its net realizable value.
Property and Equipment	Property and equipment are recorded at cost, net of accumulated depreciation and amortization. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets. Manufacturing equipment is depreciated over five years , lease and loaner instruments are depreciated over one to five years , prototype systems are depreciated over two years , computer equipment is generally depreciated over three years , furniture and fixtures are depreciated over five years and leasehold improvements are amortized over the life of the related assets or the term of the lease, whichever is shorter. Expenditures for additions are capitalized and expenditures for maintenance and repairs are expensed as incurred. Gains and losses from the disposal of property and equipment are reflected in the consolidated statements of operations in the period of disposition.
Leases and Leasehold Improvements	Rent expense for leases that provide for scheduled rent increases during the lease term is recognized on a straight-line basis over the term of the related lease. Leasehold improvements that are funded by landlord incentives or allowances are recorded in property and equipment and as a component of deferred rent and are amortized as a reduction of rent expense over the term of the related lease.
Impairment of Long-Lived Assets	The Company recognizes impairment losses on long-lived assets when indicators of impairment are present and the anticipated undiscounted cash flows to be generated by those assets are less than the asset’s carrying values. The Company has not experienced any impairment losses on its long-lived assets during the periods presented.
Segments	Operating segments are defined as components of an entity for which separate financial information is available and evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the chief executive officer, who manages the operations and evaluates the financial performance on a total Company basis. The Company’s principal operations and decision-making functions are located at its corporate headquarters in the United States and the Company operates as a single reportable segment.
Revenue Recognition	The Company recognizes revenue when (1) persuasive evidence of an arrangement exists, (2) delivery has occurred or services have been rendered, (3) the price to the customer is fixed or determinable and (4) collectability is reasonably assured. The Company generates revenue from the sale of products and services. The Company’s products consist of its proprietary nCounter Analysis System and related consumables. Services consist of extended warranties and service fees for access to new technologies still under development or for assay processing. A delivered product or service is considered to be a separate unit of accounting when it has value to the customer on a stand-alone basis. Products or services have value on a stand-alone basis if they are sold separately by any vendor or the customer could resell the delivered product. Instruments, consumables and in vitro diagnostic kits are considered to be separate units of accounting as they are sold separately and revenue is recognized upon transfer of ownership, which is generally upon shipment. Instrument revenue related to installation and calibration services is recognized when services are rendered by the Company. Such services can also be provided by the Company’s distribution partners. For instruments sold for use primarily to run Prosigna assays for diagnostic purposes, training must be provided prior to instrument revenue recognition. Instrument revenue from leased instruments is recognized ratably over the lease term. Service revenue is recognized when earned, which is generally upon the rendering of the related services. Service agreements and service fees for assay processing are each considered separate units of accounting as they are sold separately. The Company offers service agreements on its nCounter Analysis System for periods ranging from 12 to 36 months after the end of the standard 12 -month warranty period. Service agreements are generally separately priced. Revenue from service agreements is deferred and recognized on a straight-line basis over the service period. For arrangements with multiple deliverables, the Company allocates the agreement consideration at the inception of the agreement to the deliverables based upon their relative selling prices. To date, selling prices have been established by reference to vendor specific objective evidence based on stand-alone sales transactions for each deliverable. Vendor specific objective evidence is considered to have been established when a substantial majority of individual sales transactions within the previous 12-month period fall within a reasonably narrow range, which the Company has defined to be plus or minus 15% of the median sales price of actual stand-alone sales transactions. The Company uses its best estimate of selling price for individual deliverables when vendor specific objective evidence or third-party evidence is unavailable. Allocated revenue is only recognized for each deliverable when the revenue recognition criteria have been met. The Company enters into collaborative agreements that may generate upfront fees with subsequent milestone payments that may be earned upon completion of development-related milestones. The Company is able to estimate the total cost of services under the arrangements and recognizes collaboration revenue using a proportional performance model. Costs incurred to date compared to total expected costs are used to determine proportional performance, as this is considered to be representative of the delivery of outputs under the arrangements. Revenue recognized at any point in time is limited to cash received and amounts contractually due. Changes in estimates of total expected costs are accounted for prospectively as a change in estimate. From period to period, collaboration revenue can fluctuate substantially based on the achievement of development-related milestones.
Cost of Revenue	Cost of revenue consists primarily of costs incurred in the production process, including costs of purchasing instruments from third-party contract manufacturers, consumable component materials and assembly labor and overhead, installation, warranty, service and packaging and delivery costs. In addition, cost of revenue includes royalty costs for licensed technologies included in the Company’s products, provisions for slow-moving and obsolete inventory and stock-based compensation expense. Cost of revenue for instruments and consumables is recognized in the period the related revenue is recognized. Shipping and handling costs incurred for product shipments are included in cost of revenue in the consolidated statements of operations.
Reserve for Product Warranties	The Company generally provides a one -year warranty on its nCounter Analysis Systems and establishes a reserve for future warranty costs based on historical product failure rates and actual warranty costs incurred. Warranty expense is recorded as a component of cost of revenue in the consolidated statements of operations.
Research and Development	Research and development expenses, consisting primarily of salaries and benefits, occupancy costs, laboratory supplies, clinical study costs, contracted services, consulting fees and related costs, are expensed as incurred.
Selling, General and Administrative	General and administrative expenses consist primarily of personnel related costs for the Company’s finance, human resources, business development, legal, information technology and general management, as well as professional fees for legal, accounting, and other consulting services. General and administrative expenses are expensed as they are incurred. Selling expenses consist primarily of personnel related costs for sales and marketing, contracted services and service fees and are expensed as the related costs are incurred. Advertising costs are expensed as incurred and are included in sales and marketing expenses.
Income Taxes	The Company accounts for income taxes under the liability method. Under the liability method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and income tax bases of assets and liabilities and are measured using the tax rates that will be in effect when the differences are expected to reverse. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized. The Company determines whether a tax position is more likely than not to be sustained upon examination based on the technical merits of the position. For tax positions meeting the more-likely-than-not threshold, the tax amount recognized in the financial statements is reduced by the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement with the relevant tax authority.
Stock-Based Compensation	The Company accounts for stock-based compensation under the fair value method. Stock-based compensation costs are based on option awards granted and vested based on their grant-date fair value, estimated using the Black-Scholes option pricing model. The Company uses the straight-line attribution method for recognizing compensation expense.
Guarantees and Indemnifications	In the normal course of business, the Company guarantees and/or indemnifies other parties, including vendors, lessors and parties to transactions with the Company, with respect to certain matters. The Company has agreed to hold the other parties harmless against losses arising from breach of representations or covenants, or out of intellectual property infringement or other claims made against certain parties. It is not possible to determine the maximum potential amount the Company could be required to pay under these indemnification agreements, since the Company has not had any prior indemnification claims, and each claim would be based upon the unique facts and circumstances of the claim and the particular provisions of each agreement. In the opinion of management, any such claims would not be expected to have a material adverse effect on the Company’s consolidated results of operations, financial condition or cash flows.
Comprehensive Loss	Comprehensive loss includes certain changes in equity that are excluded from net loss. Specifically, unrealized gains and losses on short-term investments are included in comprehensive loss.
Recently Adopted Accounting Pronouncement and Recent Accounting Pronouncements	As an “emerging growth company,” the Jumpstart Our Business Startups Act allows the Company to delay adoption of new or revised accounting pronouncements applicable to public companies until such pronouncements are made applicable to private companies. As a result, the Company's financial statements may not be comparable to the financial statements of issuers who are required to comply with the effective dates for new or revised accounting standards that are applicable to public companies. In May 2014, FASB issued “ASU 2014-09, Revenue from Contracts with Customers.” The standard requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to a customer. In March 2016, the FASB issued “ASU 2016-08, Principal vs Agent Considerations (Reporting Revenue Gross versus Net)” which clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued “ASU 2016-10, Identifying Performance Obligations and Licensing” which clarifies the implementation guidance on identifying performance obligations and the licensing implementation guidance. In May 2016, the FASB issued “ASU 2016-12, Narrow-Scope Improvements and Practical Expedients” which provides practical expedients for contract modifications and clarification on assessing the collectability criterion, presentation of sales taxes, measurement date for noncash consideration and completed contracts at transition. The Company has formed an implementation team and completed its preliminary assessment of the potential impact of implementing this new standard. The assessment included an analysis of the Company’s current portfolio of customer contracts and related costs, as well as a review of its historical accounting policies and practices to identify potential differences in applying the new standard. The Company has determined that its collaborative agreements fall within the scope of ASC 808, Collaborative Arrangements and intends to apply the principles of ASC 606 in the measurement and recognition of revenue. In addition, the Company has concluded that service contracts will no longer be accounted for under separate accounting guidance, but rather included as separate performance obligations within a contract subject to the new standard, which includes their inclusion in the determination and allocation of the aggregate transaction price based on their relative values, and recognition of revenue upon the delivery of the performance obligation. We have determined that such service contracts comprise two performance obligations, one related to an included right to an annual preventative maintenance service included within the agreements which will be recognized when performed or the right expires, and another related to the Company's stand-ready obligations under the service contracts will be recognized over the service period. The new standard also requires more extensive disclosures related to revenue recognition, particularly in quarterly financial statements. The Company adopted the new guidance on January 1, 2018 using the modified retrospective method of adoption, has evaluated the impact of the standard on all of its revenues, including those mentioned above, and concluded the adoption of the standard will not have a material impact on its consolidated results of operations, financial condition, or cash flows. In January 2016, FASB issued “ASU 2016-01, Financial Instruments: Overall.” The standard addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. The standard will become effective for the Company beginning January 1, 2018. The Company does not anticipate adoption of this standard will have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In February 2016, FASB issued “ASU 2016-02, Leases – Recognition and Measurement of Financial Assets and Financial Liabilities.” The standard requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition. The standard requires lessors to classify leases as either sales-type, finance or operating. A sales-type lease occurs if the lessor transfers all of the risks and rewards, as well as control of the underlying asset, to the lessee. If risks and rewards are conveyed without the transfer of control, the lease is treated as a financing lease. If the lessor does not convey risks and rewards or control, an operating lease results. The standard will become effective for the Company beginning January 1, 2019. The Company is currently assessing the impact adoption of this standard will have on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In June 2016, FASB issued “ASU 2016-13, Financial Instruments: Credit Losses”. The standard provides information about expected credit losses on financial instruments at each reporting date, and to change how other than temporary impairments on investments securities are recorded. The standard will become effective for the Company beginning on January 1, 2020 with early adoption permitted. The Company is currently assessing the impact adoption of this standard will have on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In August 2016, FASB issued “ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments”. The standard provides guidance on how certain cash receipts and cash payments are presented and classified in the statement of cash flows and is intended to reduce diversity in practice with respect to these items. The standard is applied using a retrospective transition method and will become effective for the Company on January 1, 2018. The Company does not anticipate adoption of this standard will have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In November 2016, FASB issued “ASU 2016-18, Statement of Cash Flows: Restricted Cash”. The standard requires companies to include amounts generally described as restricted cash and restricted cash equivalents, along with cash and cash equivalents, when reconciling the beginning-of-period and end-of-period amounts shown on the statement of cash flows. The standard was adopted by the Company on January 1, 2018. The Company does not anticipate adoption of this standard will have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In May 2017, FASB issued “ASU 2017-09, Compensation - Stock Compensation: Scope of Modification Accounting”. The standard clarifies which changes to the terms or conditions of a share-based payment award are required to be accounted for as modifications. The standard was adopted by the Company on January 1, 2018. The adoption of this standard did not have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. Recently Adopted Accounting Pronouncement In July 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) entitled “ASU 2015-11, Inventory – Simplifying the Measurement of Inventory.” The standard requires entities to measure inventory at the lower of cost and net realizable value. The Company adopted ASU 2015-11 in the first quarter of 2017 and adoption did not have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In March 2016, FASB issued “ASU 2016-09, Improvements to Employee Share-Based Payment Accounting” which amends Accounting Standard Codification Topic 718, “Compensation – Stock Compensation”. The standard includes provisions intended to simplify various aspects related to the accounting and presentation for stock-based payments in the financial statements, including the income tax effects of stock-based payments, minimum withholding requirements upon award settlement, and the method of calculating forfeitures in the recognition of stock compensation expense. The Company adopted ASU 2016-09 in the first quarter of 2017 and has elected to account for forfeitures as they occur to determine the amount of compensation cost to be recognized. The accounting policy election was adopted applying a modified retrospective approach, and did not have a material impact on the consolidated results of operations, financial condition, cash flows, or financial statement disclosures. Employee taxes paid for withheld shares are presented as a financing activity in the consolidated statements of cash flows, as required by the new standard, and was adopted retrospectively. Other provisions of ASU 2016-09 related to the accounting for the tax effects of stock-based payments have no impact on its consolidated results of operations, as the Company records a valuation allowance for deferred tax assets related to excess tax benefits from stock-based payment transactions. Recent Accounting Pronouncements As an “emerging growth company,” the Jumpstart Our Business Startups Act allows the Company to delay adoption of new or revised accounting pronouncements applicable to public companies until such pronouncements are made applicable to private companies. As a result, the Company's financial statements may not be comparable to the financial statements of issuers who are required to comply with the effective dates for new or revised accounting standards that are applicable to public companies. In May 2014, FASB issued “ASU 2014-09, Revenue from Contracts with Customers.” The standard requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to a customer. In March 2016, the FASB issued “ASU 2016-08, Principal vs Agent Considerations (Reporting Revenue Gross versus Net)” which clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued “ASU 2016-10, Identifying Performance Obligations and Licensing” which clarifies the implementation guidance on identifying performance obligations and the licensing implementation guidance. In May 2016, the FASB issued “ASU 2016-12, Narrow-Scope Improvements and Practical Expedients” which provides practical expedients for contract modifications and clarification on assessing the collectability criterion, presentation of sales taxes, measurement date for noncash consideration and completed contracts at transition. The Company has formed an implementation team and completed its preliminary assessment of the potential impact of implementing this new standard. The assessment included an analysis of the Company’s current portfolio of customer contracts and related costs, as well as a review of its historical accounting policies and practices to identify potential differences in applying the new standard. The Company has determined that its collaborative agreements fall within the scope of ASC 808, Collaborative Arrangements and intends to apply the principles of ASC 606 in the measurement and recognition of revenue. In addition, the Company has concluded that service contracts will no longer be accounted for under separate accounting guidance, but rather included as separate performance obligations within a contract subject to the new standard, which includes their inclusion in the determination and allocation of the aggregate transaction price based on their relative values, and recognition of revenue upon the delivery of the performance obligation. We have determined that such service contracts comprise two performance obligations, one related to an included right to an annual preventative maintenance service included within the agreements which will be recognized when performed or the right expires, and another related to the Company's stand-ready obligations under the service contracts will be recognized over the service period. The new standard also requires more extensive disclosures related to revenue recognition, particularly in quarterly financial statements. The Company adopted the new guidance on January 1, 2018 using the modified retrospective method of adoption, has evaluated the impact of the standard on all of its revenues, including those mentioned above, and concluded the adoption of the standard will not have a material impact on its consolidated results of operations, financial condition, or cash flows. In January 2016, FASB issued “ASU 2016-01, Financial Instruments: Overall.” The standard addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. The standard will become effective for the Company beginning January 1, 2018. The Company does not anticipate adoption of this standard will have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In February 2016, FASB issued “ASU 2016-02, Leases – Recognition and Measurement of Financial Assets and Financial Liabilities.” The standard requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition. The standard requires lessors to classify leases as either sales-type, finance or operating. A sales-type lease occurs if the lessor transfers all of the risks and rewards, as well as control of the underlying asset, to the lessee. If risks and rewards are conveyed without the transfer of control, the lease is treated as a financing lease. If the lessor does not convey risks and rewards or control, an operating lease results. The standard will become effective for the Company beginning January 1, 2019. The Company is currently assessing the impact adoption of this standard will have on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In June 2016, FASB issued “ASU 2016-13, Financial Instruments: Credit Losses”. The standard provides information about expected credit losses on financial instruments at each reporting date, and to change how other than temporary impairments on investments securities are recorded. The standard will become effective for the Company beginning on January 1, 2020 with early adoption permitted. The Company is currently assessing the impact adoption of this standard will have on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In August 2016, FASB issued “ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments”. The standard provides guidance on how certain cash receipts and cash payments are presented and classified in the statement of cash flows and is intended to reduce diversity in practice with respect to these items. The standard is applied using a retrospective transition method and will become effective for the Company on January 1, 2018. The Company does not anticipate adoption of this standard will have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In November 2016, FASB issued “ASU 2016-18, Statement of Cash Flows: Restricted Cash”. The standard requires companies to include amounts generally described as restricted cash and restricted cash equivalents, along with cash and cash equivalents, when reconciling the beginning-of-period and end-of-period amounts shown on the statement of cash flows. The standard was adopted by the Company on January 1, 2018. The Company does not anticipate adoption of this standard will have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures. In May 2017, FASB issued “ASU 2017-09, Compensation - Stock Compensation: Scope of Modification Accounting”. The standard clarifies which changes to the terms or conditions of a share-based payment award are required to be accounted for as modifications. The standard was adopted by the Company on January 1, 2018. The adoption of this standard did not have a material impact on its consolidated results of operations, financial condition, cash flows, and financial statement disclosures.
Fair Value Measurements	The Company establishes the fair value of its assets and liabilities using the price that would be received to sell an asset or paid to transfer a financial liability in an orderly transaction between market participants at the measurement date. A fair value hierarchy is used to measure fair value. The three levels of the fair value hierarchy are as follows: • Level 1 — Quoted prices in active markets for identical assets and liabilities. • Level 2 — Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. • Level 3 — Valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable.
Net Loss Per Share	Net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding. Outstanding stock options, warrants and preferred stock have not been included in the calculation of diluted net loss per share because to do so would be anti-dilutive. Accordingly, the numerator and the denominator used in computing both basic and diluted net loss per share for each period are the same.

Short-term Investments (Tables)

Short-term Investments (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Short-Term Investments Available-for-Sale Securities	Short-term investments consisted of available-for-sale securities as follows (in thousands): Type of securities as of December 31, 2017 Amortized cost Gross unrealized gains Gross unrealized losses Fair value Corporate debt securities $ 35,567 $ — $ (53 ) $ 35,514 U.S. government-related debt securities 15,951 — (46 ) 15,905 Total available-for-sale securities $ 51,518 $ — $ (99 ) $ 51,419 Type of securities as of December 31, 2016 Amortized cost Gross unrealized gains Gross unrealized losses Fair value Corporate debt securities $ 36,198 $ 4 $ (42 ) $ 36,160 U.S. government-related debt securities 17,312 1 (20 ) 17,293 Total available-for-sale securities $ 53,510 $ 5 $ (62 ) $ 53,453
Fair Values of Available-for-Sale Securities by Contractual Maturity	The fair values of available-for-sale securities by contractual maturity at December 31 were as follows (in thousands): 2017 2016 Maturing in one year or less $ 39,985 $ 46,310 Maturing in one to three years 11,434 7,143 Total available-for-sale securities $ 51,419 $ 53,453

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Company's Available-for-Sale Securities by Level within Fair Value Hierarchy	The Company’s available-for-sale securities by level within the fair value hierarchy were as follows (in thousands): Type of securities as of December 31, 2017 Fair value measurement using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market fund $ 22,398 $ — $ — $ 22,398 Short-term investments: Corporate debt securities — 35,514 — 35,514 U.S. government-related debt securities — 15,905 — 15,905 Total $ 22,398 $ 51,419 $ — $ 73,817 Type of securities as of December 31, 2016 Fair value measurement using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market fund $ 16,715 $ — $ — $ 16,715 Short-term investments: Corporate debt securities — 36,160 — 36,160 U.S. government-related debt securities — 17,293 — 17,293 Total $ 16,715 $ 53,453 $ — $ 70,168

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consisted of the following at December 31 (in thousands): 2017 2016 Raw materials $ 5,743 $ 4,277 Work in process 4,845 4,046 Finished goods 9,469 5,489 Total inventory $ 20,057 $ 13,812

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and equipment consisted of the following at December 31 (in thousands): Useful Life (Years) 2017 2016 Manufacturing equipment 5 $ 8,395 $ 6,445 Lease and loaner instruments 1 - 5 4,106 3,581 Prototype instruments 2 2,938 2,975 Computer equipment 3 2,067 1,592 Furniture and fixtures 5 1,670 1,642 Leasehold improvements Various 11,971 8,878 Construction in progress 158 1,861 Total property and equipment, gross 31,305 26,974 Less: Accumulated depreciation and amortization (17,248 ) (14,816 ) Total property and equipment, net $ 14,057 $ 12,158

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-term debt and lease financing obligations	Long-term debt and lease financing obligations consisted of the following at December 31 (in thousands): 2017 2016 Term loans payable $ 49,315 $ 47,844 Lease financing obligations — 58 Total long-term debt and lease financing obligations 49,315 47,902 Unamortized debt issuance costs (384 ) (478 ) Current portion of lease financing obligations — (58 ) Long-term debt and lease financing obligations, net of debt issuance costs and current portion $ 48,931 $ 47,366
Scheduled Future Payments of Principal for Outstanding Debt and Lease Financing Obligations	Scheduled future payments of principal for outstanding debt and lease financing obligations were as follows at December 31: 2018 $ — 2019 — 2020 — 2021 36,987 2022 12,328 $ 49,315

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option Activity and Related Information	A summary of the Company’s stock option activity under the Plans is as follows: Shares Weighted- average exercise price per share Weighted- average remaining contractual term (in years) Aggregate intrinsic value (in thousands) Outstanding at January 1,2017 4,721,941 $ 12.00 7.41 $ 48,670 Granted 1,180,086 17.90 Canceled and forfeited (478,078 ) 15.90 Exercised (227,696 ) 4.78 Outstanding at December 31, 2017 5,196,253 $ 13.32 6.98 $ 3,861 December 31, 2017: Options vested and expected to vest 4,792,694 $ 13.07 6.84 $ 3,861 Options exercisable 3,437,421 $ 11.90 6.19 $ 3,861
Company's Options Outstanding	The following table summarizes information about the Company’s stock options outstanding at December 31, 2017 : Outstanding Exercisable Exercise Price Number of Shares Weighted- Average Remaining Contractual Life in Years Number of Shares Weighted- Average Remaining Contractual Life in Years $1.92 431,345 4.21 431,345 4.21 $2.24 – $6.72 494,155 3.87 494,155 3.87 $7.47 – $12.56 480,694 6.76 384,717 6.28 $12.77 674,356 7.06 488,124 7.04 $12.94 577,212 8.05 276,718 7.99 $13.01 – $14.95 360,230 7.62 241,553 7.42 $14.99 – $17.50 531,282 8.27 218,634 7.36 $17.89 – $18.90 1,346,556 7.63 806,525 6.66 $19.09 – $22.71 300,423 8.22 95,650 7.33 5,196,253 3,437,421
Restricted Stock Units Award Activity	A summary of RSU activity under the Plans is as follows: Non-vested RSUs Share Equivalent Weighted-Average Grant Date Fair Value Non-vested at January 1, 2017 163,602 $ 15.70 Changes during the year: Granted 603,493 10.73 Vested (66,956 ) 15.77 Forfeited (38,432 ) 17.20 Non-vested at December 31, 2017 661,707 $ 11.07
Stock Compensation Expense	The following table sets forth stock-based compensation expense related to stock-based arrangements under the Plans for the years ended December 31 as follows (in thousands): 2017 2016 2015 Cost of revenue $ 719 $ 548 $ 471 Research and development 2,853 2,046 1,453 Selling, general and administrative 7,047 5,602 3,919 Total stock-based compensation expense $ 10,619 $ 8,196 $ 5,843
Fair Value of Employee Option Grant	The fair value of each employee option grant as of December 31 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions: 2017 2016 2015 Risk-free interest rates 1.40% - 2.26% 1.18% - 2.12% 1.37% - 1.97% Expected term (years) 5.50 - 6.25 5.50 - 6.50 6.25 Expected dividend yield — — — Expected volatility 53.9% - 58.0% 47.0% 57.0%

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Loss Before Income Taxes	Loss before income taxes for the years ended December 31 consisted of the following (in thousands): 2017 2016 2015 Domestic $ (44,324 ) $ (47,562 ) $ (46,065 ) Foreign 966 589 650 Loss before income taxes $ (43,358 ) $ (46,973 ) $ (45,415 )
Significant Components of our Provision for Income Taxes	Significant components of our provision for income taxes for the years ended December 31 are as follows (in thousands): 2017 2016 2015 Current: Domestic $ — $ — $ — Foreign 204 116 166 Total provision for income taxes $ 204 $ 116 $ 166
Income Tax Expense (Benefit) Differed from Amounts Computed by Applying Statutory Federal Income Tax Rate	A reconciliation of the federal statutory income tax rate to the effective income tax rate for the years ended December 31 are as follows (in thousands): 2017 2016 2015 Income tax provision at statutory rate $ (15,076 ) $ (16,010 ) $ (15,662 ) Tax on repatriated foreign earnings and other nondeductible items 179 135 401 Change in tax credits (2,361 ) (1,449 ) (792 ) Change in valuation allowance (19,792 ) 17,824 16,706 Change in tax rate 37,690 — — Foreign tax and other (436 ) (384 ) (487 ) Total provision for income taxes $ 204 $ 116 $ 166
Effect of Temporary Differences and Carryforwards	The effect of temporary differences and carryforwards that give rise to deferred tax assets for the years ended December 31 were as follows (in thousands): 2017 2016 Net operating loss carryforwards $ 49,662 $ 70,694 Research and development tax credit carryforwards 6,505 4,572 Foreign tax credit carryforwards 448 — Stock-based compensation 5,664 5,360 Other 6,382 7,827 Total deferred tax assets 68,661 88,453 Less: Valuation allowance (68,661 ) (88,453 ) Net deferred tax assets $ — $ —
Summary of Changes in Deferred Tax Asset Valuation Allowance	The table below summarizes changes in the deferred tax asset valuation allowance for the years ended December 31 (in thousands): 2017 2016 2015 Balance at beginning of year $ 88,453 $ 70,629 $ 53,923 Charged to costs and expenses 17,898 17,824 16,706 Impact of change in tax rate (37,690 ) — — Balance at end of year $ 68,661 $ 88,453 $ 70,629
Total Balance of Unrecognized Gross Tax Benefits Resulting from R&D Credits Claimed	The total balance of unrecognized gross tax benefits for the years ended December 31, resulting from research and development tax credits claimed on the Company’s annual tax return was as follows (in thousands): 2017 2016 2015 Unrecognized tax benefits at beginning of year $ 1,524 $ 1,041 $ 777 Additions based on current year tax positions 644 483 264 Unrecognized tax benefits at end of year $ 2,168 $ 1,524 $ 1,041

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Lease Payments under Noncancelable Operating Leases	Future minimum lease payments under noncancelable operating leases as of December 31, 2017 were as follows (in thousands): 2018 $ 5,316 2019 5,307 2020 5,418 2021 5,551 2022 5,708 Thereafter 19,327 $ 46,627

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Summary of Outstanding Options, Warrants and preferred stock were Excluded from Computation of Diluted Net Loss Per Share	The following outstanding options, restricted stock units and warrants as of December 31 were excluded from the computation of diluted net loss per share for the periods presented because their effect would have been anti-dilutive (in thousands): 2017 2016 2015 Options to purchase common stock 5,335 4,711 4,069 Restricted stock units 313 115 — Common stock warrants 317 491 572

Information about Geographic 36

Information about Geographic Areas (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Classification of Revenue by Geography	The following table is based on the geographic location of distributors or end users who purchased products and services and collaborators. For sales to distributors, their geographic location may be different from the geographic locations of the ultimate end user. Revenue by geography as of December 31 was as follows (in thousands): 2017 2016 2015 Americas $ 86,099 $ 60,330 $ 41,265 Europe & Middle East 21,791 18,497 14,807 Asia Pacific 7,015 7,662 6,595 Total revenue $ 114,905 $ 86,489 $ 62,667

Condensed Quarterly Financial37

Condensed Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Condensed Quarterly Financial Data	The following table contains selected unaudited financial data for each quarter of 2017 and 2016 . The unaudited information should be read in conjunction with the Company’s financial statements and related notes included elsewhere in this report. The Company believes that the following unaudited information reflects all normal recurring adjustments necessary for a fair statement of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period. Three months ended March 31, June 30, September 30, December 31, (in thousands, except per share data) 2017 Total revenue $ 18,063 $ 34,592 $ 27,016 $ 35,234 Net loss $ (18,852 ) $ (4,555 ) $ (11,404 ) $ (8,751 ) Net loss per share – basic and diluted $ (0.87 ) $ (0.20 ) $ (0.45 ) $ (0.34 ) 2016 Total revenue $ 14,697 $ 22,627 $ 23,933 $ 25,232 Net loss $ (14,603 ) $ (10,805 ) $ (10,088 ) $ (11,593 ) Net loss per share – basic and diluted $ (0.74 ) $ (0.55 ) $ (0.51 ) $ (0.55 )

Description of the Business - A

Description of the Business - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			12 Months Ended
	Jan. 31, 2018	Jun. 30, 2017	May 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsidiary, Sale of Stock [Line Items]
Proceeds from underwritten public offering				$ 56,486	$ 26,073	$ 12,518
Underwriters partially exercised an overallotment option, additional gross proceeds				1,086	2,607	876
Proceeds from underwritten public offering after fees and commissions		$ 56,500
Proceeds from sale of common stock, net				$ 56,486	$ 26,223	$ 12,518
Sale of Stock, Number of Shares Issued in Transaction		3,450,000
Subsidiary or Equity Method Investee, Cumulative Proceeds Received on All Transactions		$ 57,800
Overallotment option
Subsidiary, Sale of Stock [Line Items]
Sale of Stock, Number of Shares Issued in Transaction		450,000
At the market equity offering
Subsidiary, Sale of Stock [Line Items]
Common stock, shares issued (in shares)					1,331,539	960,400
Proceeds from underwritten public offering after fees and commissions					$ 26,100	$ 12,500
Proceeds from sale of common stock, net	$ 40,000		$ 40,000

Significant Accounting Polici39

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Dec. 31, 2013Segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Significant Accounting Policies [Line Items]
Allowance for doubtful accounts		$ 451,600	$ 91,300	$ 2,212,600	$ 2,202,500
Allowance for doubtful accounts, additions		361,500	0	34,000
Write-offs of uncollectible accounts		1,000	5,000	0
Inventory reserves		2,700,000	2,200,000
Inventory reserves additions		900,000	800,000	200,000
Provision for inventory obsolescence		866,000	822,000	248,000
Impairment losses on long-lived assets		$ 0
Number of reportable segments | Segment	1
Standard warranty period		12 months
Percentage used to determine discount for stand-alone sales (previous 12 months)		15.00%
Product warranty accrual period		1 year
Advertising costs		$ 5,900,000	5,300,000	2,600,000
Guarantees and indemnifications liabilities		0	0
Inventory Valuation Reserve
Significant Accounting Policies [Line Items]
Provision for inventory obsolescence		$ 400,000	$ 700,000	$ 300,000
Manufacturing equipment
Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		5 years
Prototype Systems
Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		2 years
Computer equipment
Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		3 years
Furniture and fixtures
Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		5 years
Minimum
Significant Accounting Policies [Line Items]
Extended warranty period		12 months
Minimum | Lease and loaner instruments
Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		1 year
Maximum
Significant Accounting Policies [Line Items]
Extended warranty period		36 months
Maximum | Lease and loaner instruments
Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		5 years
Sales Revenue, Net | Customer Concentration Risk | Merck Sharp & Dohme Corp.
Significant Accounting Policies [Line Items]
Concentration Risk, Percentage		25.00%	13.00%
Sales Revenue, Net | Customer Concentration Risk | Medivation, Inc. and Astellas Pharma, Inc.
Significant Accounting Policies [Line Items]
Concentration Risk, Percentage		10.00%

Short-term Investments - Availa

Short-term Investments - Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 51,518	$ 53,510
Gross unrealized gains	0	5
Gross unrealized losses	(99)	(62)
Fair value	51,419	53,453
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	35,567	36,198
Gross unrealized gains	0	4
Gross unrealized losses	(53)	(42)
Fair value	35,514	36,160
U.S. government-related debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	15,951	17,312
Gross unrealized gains	0	1
Gross unrealized losses	(46)	(20)
Fair value	$ 15,905	$ 17,293

Short-term Investments - Fair V

Short-term Investments - Fair Values of Available-for-Sale Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Maturing in one year or less	$ 39,985	$ 46,310
Maturing in one to three years	11,434	7,143
Total available-for-sale securities	$ 51,419	$ 53,453

Short-term Investments - Additi

Short-term Investments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)
Investments, Debt and Equity Securities [Abstract]
Investments that were other-than-temporarily impaired	$ 0

Short-term Investments Short-te

Short-term Investments Short-term Investments - Summary of Investments in a Continuous Loss Position (Details) $ in Thousands	Dec. 31, 2017USD ($)
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	$ 35,768
Less Than 12 Months, Gross unrealized loss	93
12 Months or Greater, Fair value	3,994
12 Months or Greater, Gross unrealized losses	6
Total, Fair value	39,762
Total, Gross unrealized losses	(99)
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	26,857
Less Than 12 Months, Gross unrealized loss	53
12 Months or Greater, Fair value	0
12 Months or Greater, Gross unrealized losses	0
Total, Fair value	26,857
Total, Gross unrealized losses	(53)
U.S. government-related debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	8,911
Less Than 12 Months, Gross unrealized loss	40
12 Months or Greater, Fair value	3,994
12 Months or Greater, Gross unrealized losses	6
Total, Fair value	12,905
Total, Gross unrealized losses	$ (46)

Fair Value Measurements - Compa

Fair Value Measurements - Company's Available-for-Sale Securities by Level within Fair Value Hierarchy (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 51,419	$ 53,453
Total	73,817	70,168
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	35,514	36,160
U.S. government-related debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	15,905	17,293
Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	22,398	16,715
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	22,398	16,715
Level 1 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 | U.S. government-related debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 | Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	22,398	16,715
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	51,419	53,453
Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	35,514	36,160
Level 2 | U.S. government-related debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	15,905	17,293
Level 2 | Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0	0
Level 3 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 | U.S. government-related debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 | Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 0	$ 0

Inventory - Schedule of Invento

Inventory - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 5,743	$ 4,277
Work in process	4,845	4,046
Finished goods	9,469	5,489
Inventory, net	$ 20,057	$ 13,812

Inventory - Additional Informat

Inventory - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventory transferred into property, plant and equipment for internal use	$ 1	$ 0.8

Property and Equipment - (Detai

Property and Equipment - (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 31,305	$ 26,974
Less: Accumulated depreciation and amortization	(17,248)	(14,816)
Total property and equipment, net	$ 14,057	12,158
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Useful Life (Years)	5 years
Property and equipment, gross	$ 8,395	6,445
Lease and loaner instruments
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,106	3,581
Less: Accumulated depreciation and amortization	$ (1,900)	(1,500)
Lease and loaner instruments | Minimum
Property, Plant and Equipment [Line Items]
Useful Life (Years)	1 year
Lease and loaner instruments | Maximum
Property, Plant and Equipment [Line Items]
Useful Life (Years)	5 years
Prototype instruments
Property, Plant and Equipment [Line Items]
Useful Life (Years)	2 years
Property and equipment, gross	$ 2,938	2,975
Computer equipment
Property, Plant and Equipment [Line Items]
Useful Life (Years)	3 years
Property and equipment, gross	$ 2,067	1,592
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful Life (Years)	5 years
Property and equipment, gross	$ 1,670	1,642
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	11,971	8,878
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 158	$ 1,861

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 17,248	$ 14,816
Depreciation and amortization	3,300	2,900	$ 2,300
Lease and loaner instruments
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 1,900	$ 1,500

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Detail)	1 Months Ended		12 Months Ended
	Oct. 31, 2015USD ($)	Apr. 30, 2014USD ($)	Dec. 31, 2017USD ($)installment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jun. 30, 2016USD ($)	Oct. 31, 2014USD ($)
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity			$ 15,000,000
Term loans payable			49,315,000	$ 47,844,000
Property and equipment, net			14,057,000	12,158,000
Accumulated depreciation			17,248,000	14,816,000
Leased Property
Line of Credit Facility [Line Items]
Property and equipment, net			700,000	700,000
Accumulated depreciation			700,000	500,000
Term Loan Agreement
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity	$ 60,000,000	$ 45,000,000
Credit facility, outstanding		20,000,000
End of term payment		1,000,000
Amount of make-whole premium payment		300,000
Total charge to interest expense		1,400,000
Loss on extinguishment of debt		$ 600,000
Credit facility additional borrowing							$ 10,000,000
Percentage of accrue interest	12.00%
Percentage of deferred payment	3.00%
Deferred interest payment			4,300,000
Credit facility, additional borrowing capacity					$ 10,000,000	$ 5,000,000
Debt Instrument, Unused Borrowing Capacity, Amount				15,000,000
Term loans payable			$ 49,300,000	47,800,000
Interest payment period	7 years
Number of installments | installment			4
Percentage of redemption fee	4.00%
Percentage payment up on repayment of principal amount	2.00%
Long term liability	$ 1,100,000
Minimum liquidity covenant			$ 2,000,000
Annual revenue requirements			85,000,000
Increase in annual revenue in fiscal years			15,000,000
Interest expense			$ 6,200,000	$ 5,700,000	$ 4,000,000
Term Loan Agreement | Maximum
Line of Credit Facility [Line Items]
Percentage of accrue interest	12.50%
Term Loan Agreement | Minimum
Line of Credit Facility [Line Items]
Percentage of accrue interest	12.00%
Percentage of redemption fee	1.00%

Long-Term Debt - Long-term debt

Long-Term Debt - Long-term debt and lease financing obligations (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Term loans payable	$ 49,315	$ 47,844
Lease financing obligations	0	58
Total long-term debt and lease financing obligations	49,315	47,902
Unamortized debt issuance costs	(384)	(478)
Current portion of lease financing obligations	0	(58)
Long-term debt and lease financing obligations, net of debt issuance costs and current portion	48,931	47,366
Term Loan Agreement
Debt Instrument [Line Items]
Term loans payable	49,300	47,800
Current portion of lease financing obligations	$ 0	$ (58)

Long-Term Debt - Scheduled Futu

Long-Term Debt - Scheduled Future Payments of Principal For Outstanding Debt and Lease Financing Obligations (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Debt Disclosure [Abstract]
2,018	$ 0
2,019	0
2,020	0
2,021	36,987
2,022	12,328
Total Long Term Debt	$ 49,315

Collaboration Agreements - Addi

Collaboration Agreements - Additional Information (Detail) $ / shares in Units, $ in Thousands, shares in Millions	1 Months Ended		3 Months Ended	7 Months Ended	12 Months Ended				34 Months Ended
	Aug. 31, 2017USD ($)employee$ / sharesshares	Mar. 31, 2014USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2016USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Amount of certain milestones achieved in account receivable			$ 19,564		$ 19,564	$ 22,193			$ 22,193
Revenue recognized under collaboration agreement					42,895	17,355	$ 6,028
Deferred revenue, net of current portion			3,304		3,304	22,664			22,664
Estimated deferred revenue recognized within one year			9,229		$ 9,229	19,033			19,033
Exercise Price Of Common Stock Warrants | $ / shares					$ 10.96
Celgene Corporation | Collaborative Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments		$ 21,500
Revenue recognized under collaboration agreement							2,200
Deferred revenue recorded under collaboration agreement			5,400		$ 5,400
License and Services Revenue					200	3,200
Estimated deferred revenue recognized within one year			3,700		$ 3,700
Collaborative agreement period					1 year
Celgene Corporation | Collaborative Arrangement | Upfront Payment Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement upfront payment		5,800							$ 2,100
Proceeds from Collaborators								$ 6,000
Celgene Corporation | Collaborative Arrangement | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments		$ 27,300
Merck Sharp & Dohme Corp. | Collaborative Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from Collaborators					$ 6,800	8,700
Deferred revenue recorded under collaboration agreement			1,100		$ 1,100
Collaborative agreement period					1 year
Merck Sharp & Dohme Corp. | Collaborative Arrangement | Upfront Payment Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from Collaborators				$ 3,900		12,000
License and Services Revenue						8,500
Merck Sharp & Dohme Corp. | Collaborative Arrangement | Development Funding
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from Collaborators							3,900
Merck Sharp & Dohme Corp. | Clinical Collaborative Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License and Services Revenue					$ 27,000	8,600	$ 3,700
Estimated deferred revenue recognized within one year			1,000		1,000
Medivation, Inc. and Astellas Pharma, Inc. | Collaborative Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from Collaborators					900	2,400
License and Services Revenue					11,500	4,800
Termination penalty					1,000
Medivation, Inc. and Astellas Pharma, Inc. | Collaborative Arrangement | Upfront Payment Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from Collaborators						$ 6,000
Lam Research Corporation [Member] | Collaborative Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from Collaborators			13,400
License and Services Revenue					3,700
Maximum Amount Of Royalties Payable, Ratio To License And Service Revenue	3
Reimbursement Of Counterparty Costs, Maximum Number Of Employees | employee	10
Exercise Price Of Common Stock Warrants | $ / shares	$ 16.75
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants	$ 6,700
Other Liabilities, Current			$ 8,300		$ 8,300
Lam Research Corporation [Member] | Collaborative Arrangement | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License and Services Revenue	$ 50,000
Class of Warrant or Right, Outstanding | shares	1

Common Stock and Preferred St53

Common Stock and Preferred Stock - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017Vote$ / sharesshares	Dec. 31, 2016shares
Equity [Abstract]
Each share of common stock is entitled to vote | Vote	1
Preferred stock, shares authorized (in shares)	15,000,000	15,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0
Preferred stock warrants were converted into warrants to purchase common stock (in shares)	355,585
Exercise price of common stock warrants (in dollars per share) | $ / shares	$ 10.96

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Jul. 31, 2013	Dec. 31, 2017USD ($)employee$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value per share (in dollars per share) | $ / shares		$ 9.08	$ 6.79	$ 7.07
Aggregate intrinsic value for options exercised		$ 2,400,000	$ 5,000,000	$ 2,100,000
Fair value of options vested		8,900,000	6,800,000	6,500,000
Unrecognized compensation cost		$ 19,200,000
Unrecognized compensation cost, weighted-average recognized period		2 years 4 months 6 days
Tax benefit recognized related to share-based compensation cost		$ 0
Total share-based compensation expense		$ 11,369,000	9,038,000	$ 6,278,000
2004 Stock Option Plan and 2013 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under the Plans (in shares) | shares		7,501,801
Stock options grant period, years		10 years
Stock options vesting period and exercisable period, years		4 years
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees affected | employee		109
Number of shares modified | shares		265,000
Incremental compensation cost		$ 50,000
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total value of shares vested		$ 1,083,000	$ 64,000
Shares vested (in shares) | shares		66,956	0	0
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Length of offering period, in months	12 months
Length of purchase periods, in months	6 months
Purchase price percentage of fair market value of shares	85.00%
Shares issued (in shares) | shares		138,972	139,195	136,078
Total share-based compensation expense		$ 800,000	$ 800,000	$ 400,000
Common stock reserved for issuance (in shares) | shares		825,442
Share available for grant (in shares) | shares		269,811
ESPP | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contribution percentage of purchase shares on participants eligible compensation	0.00%
ESPP | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contribution percentage of purchase shares on participants eligible compensation	10.00%

Stock-based Compensation - Stoc

Stock-based Compensation - Stock Option Activity and Related Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at December 31, 2015 (in shares)	4,721,941
Granted (in shares)	1,180,086
Canceled and forfeited (in shares)	(478,078)
Exercised (in shares)	(227,696)
Outstanding at December 31, 2016 (in shares)	5,196,253	4,721,941
Options vested and expected to vest at December 31, 2016 (in shares)	4,792,694
Options exercisable at December 31, 2016 (in shares)	3,437,421
Weighted- average exercise price per share
Outstanding at December 31, 2015 (in dollars per share)	$ 12
Granted (in dollars per share)	17.90
Canceled and forfeited (in dollars per share)	15.90
Exercised (in dollars per share)	4.78
Outstanding at December 31, 2016 (in dollars per share)	13.32	$ 12
Options vested and expected to vest at December 31, 2016 (in dollars per share)	13.07
Options exercisable at December 31, 2016 (in dollars per share)	$ 11.90
Weighted- average remaining contractual term (in years)
Outstanding	6 years 11 months 23 days	7 years 4 months 28 days
Options vested and expected to vest as December 31, 2016	6 years 10 months 2 days
Options exercisable at December 31, 2016	6 years 2 months 9 days
Aggregate intrinsic value (in thousands)
Outstanding	$ 3,861	$ 48,670
Options vested and expected to vest at December 31, 2016	3,861
Options exercisable at December 31, 2016	$ 3,861

Stock-based Compensation - Comp

Stock-based Compensation - Company's Options Outstanding (Detail)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding - Number of Shares (in shares)	5,196,253
Options Exercisable - Number of Shares (in shares)	3,437,421
$ 1.92
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Minimum (in dollars per share) | $ / shares	$ 0
Exercise Price, Maximum (in dollars per share) | $ / shares	$ 1.92
Options Outstanding - Number of Shares (in shares)	431,345
Options Outstanding -Weighted- Average Remaining Contractual Life in Years	4 years 2 months 16 days
Options Exercisable - Number of Shares (in shares)	431,345
Options Exercisable - Weighted- Average Remaining Contractual Life in Years	4 years 2 months 16 days
$2.24 – $6.72
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Minimum (in dollars per share) | $ / shares	$ 2.24
Exercise Price, Maximum (in dollars per share) | $ / shares	$ 6.72
Options Outstanding - Number of Shares (in shares)	494,155
Options Outstanding -Weighted- Average Remaining Contractual Life in Years	3 years 10 months 12 days
Options Exercisable - Number of Shares (in shares)	494,155
Options Exercisable - Weighted- Average Remaining Contractual Life in Years	3 years 10 months 12 days
$7.47 – $12.56
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Minimum (in dollars per share) | $ / shares	$ 8.96
Exercise Price, Maximum (in dollars per share) | $ / shares	$ 12.60
Options Outstanding - Number of Shares (in shares)	480,694
Options Outstanding -Weighted- Average Remaining Contractual Life in Years	6 years 9 months 2 days
Options Exercisable - Number of Shares (in shares)	384,717
Options Exercisable - Weighted- Average Remaining Contractual Life in Years	6 years 3 months 12 days
$ 12.77
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Minimum (in dollars per share) | $ / shares	$ 12.77
Exercise Price, Maximum (in dollars per share) | $ / shares	$ 12.77
Options Outstanding - Number of Shares (in shares)	674,356
Options Outstanding -Weighted- Average Remaining Contractual Life in Years	7 years 22 days
Options Exercisable - Number of Shares (in shares)	488,124
Options Exercisable - Weighted- Average Remaining Contractual Life in Years	7 years 15 days
$ 12.94
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Minimum (in dollars per share) | $ / shares	$ 12.94
Exercise Price, Maximum (in dollars per share) | $ / shares	$ 12.94
Options Outstanding - Number of Shares (in shares)	577,212
Options Outstanding -Weighted- Average Remaining Contractual Life in Years	8 years 17 days
Options Exercisable - Number of Shares (in shares)	276,718
Options Exercisable - Weighted- Average Remaining Contractual Life in Years	7 years 11 months 27 days
$13.01 – $14.95
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Minimum (in dollars per share) | $ / shares	$ 13.01
Exercise Price, Maximum (in dollars per share) | $ / shares	$ 14.95
Options Outstanding - Number of Shares (in shares)	360,230
Options Outstanding -Weighted- Average Remaining Contractual Life in Years	7 years 7 months 14 days
Options Exercisable - Number of Shares (in shares)	241,553
Options Exercisable - Weighted- Average Remaining Contractual Life in Years	7 years 5 months 2 days
$14.99 – $17.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Minimum (in dollars per share) | $ / shares	$ 14.99
Exercise Price, Maximum (in dollars per share) | $ / shares	$ 17.50
Options Outstanding - Number of Shares (in shares)	531,282
Options Outstanding -Weighted- Average Remaining Contractual Life in Years	8 years 3 months 9 days
Options Exercisable - Number of Shares (in shares)	218,634
Options Exercisable - Weighted- Average Remaining Contractual Life in Years	7 years 4 months 10 days
$17.89 – $18.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Minimum (in dollars per share) | $ / shares	$ 17.89
Exercise Price, Maximum (in dollars per share) | $ / shares	$ 18.90
Options Outstanding - Number of Shares (in shares)	1,346,556
Options Outstanding -Weighted- Average Remaining Contractual Life in Years	7 years 7 months 16 days
Options Exercisable - Number of Shares (in shares)	806,525
Options Exercisable - Weighted- Average Remaining Contractual Life in Years	6 years 7 months 28 days
$19.09 – $22.71
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Minimum (in dollars per share) | $ / shares	$ 19.09
Exercise Price, Maximum (in dollars per share) | $ / shares	$ 22.71
Options Outstanding - Number of Shares (in shares)	300,423
Options Outstanding -Weighted- Average Remaining Contractual Life in Years	8 years 2 months 20 days
Options Exercisable - Number of Shares (in shares)	95,650
Options Exercisable - Weighted- Average Remaining Contractual Life in Years	7 years 4 months

Stock-based Compensation - Rest

Stock-based Compensation - Restricted Stock Units (RSUs) Activity (Details) - Restricted stock units - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested at December 31, 2015 (in shares)	163,602
Granted (in shares)	603,493
Vested (in shares)	(66,956)	0	0
Forfeited (in shares)	(38,432)
Non-vested at December 31, 2016 (in shares)	661,707	163,602
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Non-vested at December 31, 2015 (in dollars per share)	$ 15.70
Granted (in dollars per share)	10.73
Vested (in dollars per share)	15.77
Forfeited (in dollars per share)	17.20
Non-vested at December 31, 2016 (in dollars per share)	$ 11.07	$ 15.70

Stock-based Compensation - St58

Stock-based Compensation - Stock Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 10,619	$ 8,196	$ 5,843
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	719	548	471
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,853	2,046	1,453
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 7,047	$ 5,602	$ 3,919

Stock-based Compensation - Fair

Stock-based Compensation - Fair Value of Employee Option Grant (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)			6 years 3 months
Expected dividend yield	0.00%	0.00%	0.00%
Expected volatility		47.00%	57.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rates	1.40%	1.18%	1.37%
Expected term (years)	5 years 6 months	5 years 6 months
Expected volatility	53.90%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rates	2.26%	2.12%	1.97%
Expected term (years)	6 years 3 months	6 years 6 months
Expected volatility	58.00%

Defined Contribution Retireme60

Defined Contribution Retirement Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Contribution for retirement plan	$ 1.2	$ 0.9	$ 0.5

Income Taxes - Loss Before Inco

Income Taxes - Loss Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ (44,324)	$ (47,562)	$ (46,065)
Foreign	966	589	650
Net loss before provision for income taxes	$ (43,358)	$ (46,973)	$ (45,415)

Income Taxes - Significant Comp

Income Taxes - Significant Components of our Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Federal, State and Local, Tax Expense (Benefit) [Abstract]
Total provision for income taxes	$ 204	$ 116	$ 166
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	37,690	0
Geographic Distribution, Domestic [Member]
Current Federal, State and Local, Tax Expense (Benefit) [Abstract]
Total provision for income taxes	$ 0	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes And Tax Related [Line Items]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 37,690	$ 0
Accrued interest and penalties recorded	0	$ 0	$ 0
Federal and State
Income Taxes And Tax Related [Line Items]
Net operating loss carryforwards	232,800
Tax credit carryforwards	$ 7,000

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Benefit) Differed from Amounts Computed by Applying Statutory Federal Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income tax provision at statutory rate	$ (15,076)	$ (16,010)	$ (15,662)
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings and Other Nondeductible Amounts	179	135	401
Change in tax credits	(2,361)	(1,449)	(792)
Change in valuation allowance	(19,792)	17,824	16,706
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	37,690	0
Foreign tax and other	(436)	(384)	(487)
Total provision for income taxes	$ 204	$ 116	$ 166

Income Taxes - Effect of Tempor

Income Taxes - Effect of Temporary Differences and Carryforwards (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 49,662	$ 70,694
Research and development tax credit carryforwards	6,505	4,572
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	448	0
Stock-based compensation	5,664	5,360
Other	6,382	7,827
Total deferred tax assets	68,661	88,453
Less: Valuation allowance	(68,661)	(88,453)	$ (70,629)	$ (53,923)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Summary of Chang

Income Taxes - Summary of Changes in Deferred Tax Asset Valuation Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 88,453	$ 70,629	$ 53,923
Balance at End of Year	68,661	88,453	70,629
Valuation Allowance of Deferred Tax Assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Charged to Costs and Expenses	17,898	17,824	16,706
Write-offs	$ (37,690)	$ 0	$ 0

Income Taxes - Total Balance of

Income Taxes - Total Balance of Unrecognized Gross Tax Benefits Resulting from R&D Credits Claimed (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of year	$ 1,524	$ 1,041	$ 777
Additions based on current year tax positions	644	483	264
Unrecognized tax benefits at end of year	$ 2,168	$ 1,524	$ 1,041

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)ft²Lease	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Commitments and Contingencies Disclosure [Abstract]
Number of operating leases | Lease	3
General office, laboratory, and research and development space leased | ft²	106,740
Deferred rent liability	$ 8.7	$ 7.5
Operating lease agreement rent expense	4.8	$ 3.8	$ 3.2
Non cancellable purchase obligations	$ 4.4

Commitments and Contingencies69

Commitments and Contingencies - Future Minimum Lease Payments under Noncancelable Operating Leases (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,017	$ 5,316
2,018	5,307
2,019	5,418
2,020	5,551
2,021	5,708
Thereafter	19,327
Total	$ 46,627

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Outstanding Options, Warrants and preferred stock were Excluded from Computation of Diluted Net Loss Per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share (in shares)	5,335	4,711	4,069
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share (in shares)	313	115	0
Common Stock | Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share (in shares)	317	491	572

Information about Geographic 71

Information about Geographic Areas - Classification of Revenue by Geography (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 35,234	$ 27,016	$ 34,592	$ 18,063	$ 25,232	$ 23,933	$ 22,627	$ 14,697	$ 114,905	$ 86,489	$ 62,667
Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									86,099	60,330	41,265
Europe & Middle East
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									21,791	18,497	14,807
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									$ 7,015	$ 7,662	$ 6,595

Information about Geographic 72

Information about Geographic Areas - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 35,234	$ 27,016	$ 34,592	$ 18,063	$ 25,232	$ 23,933	$ 22,627	$ 14,697	$ 114,905	$ 86,489	$ 62,667
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									$ 84,000	$ 58,000	$ 37,900

Condensed Quarterly Financial73

Condensed Quarterly Financial Data (unaudited) - Schedule of Condensed Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 35,234	$ 27,016	$ 34,592	$ 18,063	$ 25,232	$ 23,933	$ 22,627	$ 14,697	$ 114,905	$ 86,489	$ 62,667
Net loss	$ (8,751)	$ (11,404)	$ (4,555)	$ (18,852)	$ (11,593)	$ (10,088)	$ (10,805)	$ (14,603)	$ (43,562)	$ (47,089)	$ (45,581)
Net loss per share - basic and diluted (in dollars per share)	$ (0.34)	$ (0.45)	$ (0.20)	$ (0.87)	$ (0.55)	$ (0.51)	$ (0.55)	$ (0.74)	$ (1.84)	$ (2.34)	$ (2.40)

Subsequent Events Subsequent 74

Subsequent Events Subsequent Events (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Jan. 31, 2018	May 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Proceeds from sale of common stock, net			$ 56,486	$ 26,223	$ 12,518
Credit facility, maximum borrowing capacity			$ 15,000
At the market equity offering
Subsequent Event [Line Items]
Proceeds from sale of common stock, net	$ 40,000	$ 40,000