Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2017	Oct. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Trading Symbol	TTOO
Entity Registrant Name	T2 Biosystems, Inc.
Entity Central Index Key	0001492674
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		35,824,960

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 52,897	$ 73,488
Accounts receivable	442	327
Prepaid expenses and other current assets	754	820
Inventories, net	1,254	803
Total current assets	55,347	75,438
Property and equipment, net	13,854	13,589
Restricted cash	260	260
Other assets	218	281
Total assets	69,679	89,568
Current liabilities:
Accounts payable	993	962
Accrued expenses and other current liabilities	5,513	4,908
Current portion of notes payable	1,416	1,269
Deferred revenue	2,076	2,445
Current portion of lease incentives	247	301
Total current liabilities	10,245	9,885
Notes payable, net of current portion	40,089	39,504
Lease incentives, net of current portion	751	792
Other liabilities	467	49
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized; no shares issued and outstanding at September 30, 2016 and December 31, 2016
Common stock, $0.001 par value; 200,000,000 shares authorized; 35,796,722 and 30,482,712 shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively	36	30
Additional paid-in capital	266,014	242,997
Accumulated deficit	(247,923)	(203,689)
Total stockholders’ equity	18,127	39,338
Total liabilities and stockholders’ equity	$ 69,679	$ 89,568

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	35,796,722	30,482,712
Common stock, shares outstanding	35,796,722	30,482,712

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue:
Product revenue	$ 739	$ 580	$ 2,105	$ 1,168
Research revenue	369	504	900	2,003
Total revenue	1,108	1,084	3,005	3,171
Costs and expenses:
Cost of product revenue	2,106	1,894	5,722	4,701
Research and development	5,880	5,200	19,577	18,160
Selling, general and administrative	5,559	5,935	17,192	18,282
Total costs and expenses	13,545	13,029	42,491	41,143
Loss from operations	(12,437)	(11,945)	(39,486)	(37,972)
Interest expense, net	(1,718)	(876)	(5,008)	(2,416)
Other income, net	79	38	260	133
Net loss and comprehensive loss	$ (14,076)	$ (12,783)	$ (44,234)	$ (40,255)
Net loss per share — basic and diluted	$ (0.45)	$ (0.51)	$ (1.43)	$ (1.64)
Weighted-average number of common shares used in computing net loss per share — basic and diluted	31,420,726	25,027,751	30,873,930	24,524,508

Condensed Consolidated Statement of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net loss	$ (44,234)	$ (40,255)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,194	1,626
Stock-based compensation expense	3,806	3,659
Loss on sale of T2 owned equipment	134
Non-cash interest expense	1,968	459
Deferred rent	(95)	(187)
Changes in operating assets and liabilities:
Accounts receivable	(115)	(10)
Prepaid expenses and other assets	129	(118)
Inventories, net	(451)	(654)
Accounts payable	31	(132)
Accrued expenses and other liabilities	361	797
Deferred revenue	(369)	(1,328)
Net cash used in operating activities	(36,641)	(36,143)
Cash flows from investing activities
Purchases of property and equipment	(843)
Purchases of T2-owned equipment	(1,758)	(4,594)
Net cash used in investing activities	(2,601)	(4,594)
Cash flows from financing activities
Payment of offering costs for issuance of common stock in public offering	(37)	(385)
Proceeds from issuance of common stock and stock options exercises, net	717	736
Proceeds from issuance of common stock in connection with private offering, net of offering costs	37
Proceeds from private investment in public entity		39,723
Proceeds from confidentially marketed public offering	18,832
Proceeds from notes payable, net of issuance costs		4,593
Repayments of note payable	(898)	(2,481)
Net cash provided by financing activities	18,651	42,186
Net decrease in cash and cash equivalents	(20,591)	1,449
Cash and cash equivalents at beginning of period	73,488	73,662
Cash and cash equivalents at end of period	52,897	75,111
Supplemental disclosures of cash flow information
Cash paid for interest	2,967	1,881
Supplemental disclosures of noncash investing and financing activities
Accrued property and equipment	$ 90	$ 133

Nature of Business	9 Months Ended
Nature of Business	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business	1. Nature of Business T2 Biosystems, Inc. (the “Company”) was incorporated on April 27, 2006 as a Delaware corporation with operations based in Lexington, Massachusetts. The Company is an in vitro diagnostics company that has developed an innovative and proprietary technology platform that offers a rapid, sensitive and simple alternative to existing diagnostic methodologies. The Company is using its T2 Magnetic Resonance technology (“T2MR”) to develop a broad set of applications aimed at lowering mortality rates, improving patient outcomes and reducing the cost of healthcare by helping medical professionals make targeted treatment decisions earlier. T2MR enables rapid detection of pathogens, biomarkers and other abnormalities in a variety of unpurified patient sample types, including whole blood, plasma, serum, saliva, sputum and urine, and can detect cellular targets at limits of detection as low as one colony forming unit per milliliter (“CFU/mL”). The Company’s initial development efforts target sepsis and lyme disease, which are areas of significant unmet medical need in which existing therapies could be more effective with improved diagnostics. On September 22, 2014, the Company received market clearance from the U.S. Food and Drug Administration (“FDA”) for its first two products, the T2Dx Instrument (the “T2Dx”) and T2Candida Panel (“T2Candida”). On June 30, 2017 the Company received a CE Mark for its T2Bacteria Panel (“T2Bacteria”). On September 8, 2017 the Company filed a 510(k) premarket submission for the T2Bacteria Panel with the U.S. Food and Drug Administration (FDA). Liquidity At September 30, 2017, the Company had cash and cash equivalents of $52.9 million and an accumulated deficit of $247.9 million. The future success of the Company is dependent on its ability to successfully commercialize its FDA approved products, obtain regulatory clearance for and successfully launch its future product candidates, including T2Bacteria, obtain additional capital and ultimately attain profitable operations. Historically, the Company has funded its operations primarily through its August 2014 initial public offering, its December 2015 confidentially marketed public offering (“CMPO”), its September 2016 private investment in public equity (“PIPE”) financing, its September 2017 CMPO, private placements of redeemable convertible preferred stock and through debt financing arrangements. The Company is subject to a number of risks similar to other newly commercial life science companies, including, but not limited to commercially launching the Company’s products, development and market acceptance of the Company’s product candidates, development by its competitors of new technological innovations, protection of proprietary technology, and raising additional capital. Having obtained authorization from the FDA to market T2Dx and T2Candida, the Company has incurred significant commercialization expenses related to product sales, marketing, manufacturing and distribution. The Company will continue the research and development of other product candidates and maintain, expand and protect its intellectual property portfolio. The Company may seek to fund its operations through public equity or private equity or debt financings, as well as other sources. However, the Company may be unable to raise additional funds or enter into such other arrangements when needed on favorable terms or at all. The Company’s failure to raise capital or enter into such other arrangements if and when needed would have a negative impact on the Company’s business, results of operations and financial condition and the Company’s ability to develop and commercialize T2Dx, T2Candida, T2Bacteria and other product candidates. Management believes that its existing cash and cash equivalents at September 30, 2017, together with the additional remaining liquidity on the Company’s Term Loan Agreement of up to an additional $10.0 million, will be sufficient to allow the Company to fund its current operating plan through early 2019. The borrowing on the Term Loan Agreement is available at any time through July 27, 2018, and is subject to certain conditions including that the Company receive 510(k) clearance for the marketing of T2Bacteria by the FDA by April 30, 2018 (see Note 5). Should the Company’s current operating plan not materialize as expected, including the Company’s ability to draw additional borrowings on the Term Loan Agreement on a timely basis, the Company would delay certain research projects and capital expenditures and reduce or eliminate certain future operating expenses in order to fund operations at reduced levels for the Company to continue as a going concern for a period of 12 months from the date the financial statements are issued. For more information, refer to the section titled “Liquidity and Capital Resources” in Item 2, Management’s Discussion and Analysis of Financial Condition and Results of Operations and the section entitled “Risk Factors” in the Annual Report on Form 10-K for the year ended December 31, 2016, for additional risks associated with our capital needs.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The Company’s financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States GAAP as defined in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). The Company’s condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, T2 Biosystems Securities Corporation. All intercompany balances and transactions have been eliminated.

We have evaluated subsequent events from September 30, 2017 through the date of the issuance of these condensed consolidated financial statements and have determined that no material subsequent events have occurred that would have a material effect on the information presented in these consolidated financial statements.

Unaudited Interim Financial Information

Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.

The accompanying interim condensed consolidated balance sheet as of September 30, 2017, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2017 and 2016, the condensed consolidated statements of cash flows for the nine months ended September 30, 2017 and 2016 and the related financial data and other information disclosed in these notes are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements, and, in the opinion of management, reflect all adjustments, consisting of normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2017, and the results of its operations and its cash flows for the three and nine months ended September 30, 2017 and 2016. The results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results to be expected for the year ending December 31, 2017, any other interim periods, or any future year or period.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the Chief Executive Officer. The Company views its operations and manages its business in one operating segment, which is the business of developing and, upon regulatory clearance, launching commercially its diagnostic products aimed at lowering mortality rates, improving patient outcomes and reducing the cost of healthcare by helping medical professionals make targeted treatment decisions earlier.

Net Loss Per Share

Basic net loss per share is calculated by dividing net loss by the weighted-average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting the weighted-average number of shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the diluted net loss per share calculation, stock options and unvested restricted stock are considered to be common stock equivalents, but have been excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive for all periods presented. Therefore, basic and diluted net loss per share applicable to common stockholders was the same for all periods presented.

Guarantees

As permitted under Delaware law, the Company indemnifies its officers and directors for certain events or occurrences while each such officer or director is, or was, serving at the Company’s request in such capacity. The term of the indemnification is the officer’s or director’s lifetime. The maximum potential amount of future payments the Company could be required to make is unlimited; however, the Company has directors’ and officers’ liability insurance coverage that limits its exposure and enables the Company to recover a portion of any future amounts paid.

The Company leases office, laboratory and manufacturing space under noncancelable operating leases. The Company has standard indemnification arrangements under the leases that require it to indemnify the landlords against all costs, expenses, fines, suits, claims, demands, liabilities, and actions directly resulting from any breach, violation or nonperformance of any covenant or condition of the Company’s leases.

In the ordinary course of business, the Company enters into indemnification agreements with certain suppliers and business partners where the Company has certain indemnification obligations limited to the costs, expenses, fines, suits, claims, demands, liabilities and actions directly resulting from the Company’s gross negligence or willful misconduct, and in certain instances, breaches, violations or nonperformance of covenants or conditions under the agreements.

As of September 30, 2017 and December 31, 2016, the Company had not experienced any material losses related to these indemnification obligations, and no material claims with respect thereto were outstanding. The Company does not expect significant claims related to these indemnification obligations and, consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established.

Revenue Recognition

The Company generates revenue from product sales, which includes the sale of instruments, consumable diagnostic tests and related services, and research and development agreements with third parties. The Company recognizes revenue in accordance with FASB ASC Topic 605, Revenue Recognition (“ASC 605”). Accordingly, the Company recognizes revenue when all of the following criteria have been met:

Persuasive evidence of an arrangement exists

ii.

Delivery has occurred or services have been rendered

iii.

The seller’s price to the buyer is fixed or determinable

iv.

Collectability is reasonably assured

If any of the above criteria have not been met, the Company defers revenue until such time each of the criteria have been satisfied.

Product revenue is generated by the sale of instruments and consumable diagnostic tests predominantly through the Company’s direct sales force in the United States and distributors in geographic regions outside the United States. The Company does not offer product return or exchange rights (other than those relating to defective goods under warranty) or price protection allowances to its customers, including its distributors. Payment terms granted to distributors are the same as those granted to end-user customers and payments are not dependent upon the distributors’ receipt of payment from their end-user customers. The Company either sells instruments to customers and international distributors, or retains title and places the instrument at the customer site pursuant to a reagent rental agreement. When the instrument is directly purchased by a customer, the Company recognizes revenue when all applicable revenue recognition criteria are met. When the instrument is placed under a reagent rental agreement, the Company’s customers generally agree to fixed term agreements, which can be extended, certain of which may include minimum purchase commitments and/or incremental charges on each consumable diagnostic test purchased, which varies based on the volume of test cartridges purchased. Revenue from the sale of consumable diagnostic tests, which includes the incremental charge, is recognized upon delivery or shipment as a component of product revenue in the Company’s consolidated statements of operations and comprehensive loss.

Direct sales of instruments include warranty, maintenance and technical support services typically for one year following the installation of the purchased instrument (“Maintenance Services”). After the completion of the initial Maintenance Services period, customers have the option to renew the Maintenance Services typicallyfor additional one year periods in exchange for additional consideration. In addition, the Company may provide training to customers. The Company defers revenue from the initial sale of the instrument equal to the relative fair value of the one year of Maintenance Services and training and recognizes the amounts ratably over the service delivery period.

The Company warrants that consumable diagnostic tests will be free from defects, when handled according to product specifications, for the stated life of the product. To fulfill valid warranty claims, the Company either provides a credit to its customers on future orders or provides a replacement product. Accordingly, the Company defers revenue associated with the estimated defect rates of the consumable diagnostic tests.

The Company does not offer rights of return for instruments or consumable diagnostic tests.

Shipping and handling costs incurred associated with products sold to customers are recorded as a cost of product revenue in the consolidated statement of operations and comprehensive loss. Shipping and handling costs billed to customers in connection with a product sale are recorded as a component of product revenue in the consolidated statements of operations and comprehensive loss.

For multiple-element arrangements, the Company identifies the deliverables included within each agreement and evaluates which deliverables represent separate units of accounting. The determination that multiple elements in an arrangement meet the criteria for separate units of accounting requires the Company’s management to exercise judgment. The Company accounts for those components as separate elements when the following criteria are met: (1) the delivered items have value to the customer on a stand-alone basis; and, (2) if there is a general right of return relative to the delivered items, delivery or performance of the undelivered items is considered probable and within its control.

The consideration received is allocated among the separate units of accounting based on a selling price hierarchy. The selling price hierarchy is based on: (1) vendor specific objective evidence (“VSOE”), if available; (2) third party evidence of selling price if VSOE is not available; or (3) best estimated selling price (“BESP”) if neither VSOE nor third party evidence is available. The Company generally expects that it will not be able to establish selling price using third-party evidence due to the nature of our products and the markets in which the Company competes, and, as such, the Company typically will determine selling price using VSOE or BESP.

When the Company establishes selling price using BESP, consideration is given to both market and Company-specific factors, including the cost to produce the deliverable and the anticipated margin on that deliverable, as well as the characteristics of markets in which the deliverable is sold.

Revenue earned from activities performed pursuant to research and development agreements is reported as research revenue in the consolidated statements of operations and comprehensive loss, using the proportional performance method as the work is completed, limited to payments earned, and the related costs are expensed as incurred as research and development expense. The timing of receipt of cash from the Company’s research and development agreements generally differs from when revenue is recognized.

Product Recall

In July 2016, the Company initiated a voluntary recall and replacement of its T2Candida cartridges at certain customer sites because T2Candida was experiencing higher than normal invalid test rates as the T2Candida cartridges aged. As of September 30, 2016, as a result of this voluntary recall, the Company deferred revenue totaling $149,000 and recorded additional costs of product revenue of $41,000 related to returned products, which are no longer usable. As of September 30, 2017, the Company had $20,000 of deferred revenue and $2,000 of warranty reserve remaining, both related to this voluntary recall. The impact of the voluntary recall on T2Candida cartridges in inventory was not material to the condensed consolidated financial statements.

Cost of Product Revenue

Cost of product revenue includes the cost of materials, direct labor and manufacturing overhead costs used in the manufacture of consumable diagnostic tests sold to customers and related license and royalty fees. Cost of product revenue also includes depreciation on revenue generating T2Dx instruments that have been placed with customers under reagent rental agreements; costs of materials, direct labor and manufacturing overhead costs on the T2Dx instruments sold to customers; and other costs such as customer support costs, royalties and license fees, warranty and repair and maintenance expense on the T2Dx instruments that have been placed with customers under reagent rental agreements.

Research and Development Costs

Costs incurred in the research and development of the Company’s product candidates are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including activities associated with performing services under research revenue arrangements, and include salaries and benefits, stock compensation, research-related facility and overhead costs, laboratory supplies, equipment and contract services.

Recent Accounting Standards

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption.

Accounting Standards Adopted

In August 2014, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2014-15, “Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern” which is intended to define management’s responsibility to evaluate whether there is substantial doubt about an organization’s ability to continue as a going concern and to provide related footnote disclosures. Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its financial obligations as they become due within one year after the date that the financial statements are issued (or are available to be issued). ASU No. 2014-15 provides guidance to an organization’s management, with principles and definitions intended to reduce diversity in the timing and content of disclosures commonly provided by organizations in the footnotes of their financial statements. ASU No. 2014-15 was effective for annual reporting periods ending after December 15, 2016, and for annual and interim periods thereafter. This standard has been adopted and reflected in the Company’s disclosures regarding liquidity.

In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory (“ASU 2015-11”). The standard simplifies the subsequent measurement of inventory by requiring inventory to be measured at the lower of cost and net realizable value for entities using the first-in-first out method of valuing inventory. ASU 2015-11 eliminates other measures required by current guidance to determine net realizable value. ASU 2015-11 is effective for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years and early adoption is permitted. The Company’s adoption of this standard did not have a material effect on its condensed consolidated financial statements.

In March 2016, the FASB released ASU No. 2016-09 Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”) which is intended to simplify income tax accounting for excess tax benefits, accounting for forfeitures, and employer statutory withholding. Under the current guidance, excess tax benefits that result from an award vesting or settling are recognized in additional paid-in capital in the period that they reduce cash taxes payable. This requires the provision to be computed on a with and without option basis and may result in net operating loss and credit carryforwards on the balance sheet being less than what is available on the tax return. Under the new guidance, the income tax effects of awards will be recognized as a component of income tax expense when the awards vest or are settled (regardless if cash taxes are reduced). For interim reporting purposes, companies will account for excess tax benefits and tax deficiencies as discrete items in the period during which they occurred. The guidance is effective for public entities for fiscal years beginning after December 15, 2016, and interim periods within those years. Early adoption is permitted, however all of the guidance included in the update must be applied when adopted. The Company must use a modified retrospective transition method for adopting and record the cumulative effect of all unrecognized benefits and any change in valuation allowances at the end of the prior tax period as an adjustment to retained earnings. The Company’s adoption of this standard did not have a material effect on its condensed consolidated financial statements and prior periods have not been adjusted. As a result, the Company established a net operating loss deferred tax asset of $1.2 million to account for prior period excess tax benefits through retained earnings, however an offsetting valuation allowance of $1.2 million will also be established through retained earnings because it is not more likely than not that the deferred tax asset will be realized due to historical and expected future losses, such that there is no impact on the Company’s condensed consolidated financial statements. The Company also elected to maintain the use of estimated forfeitures in the calculation of stock based compensation.

In March 2016, the FASB issued ASU No. 2016-06, Derivatives and Hedging (Topic 815): Contingent Put and Call Options in Debt Instruments (“ASU 2016-06”), which applies to all issuers of or investors in debt instruments with embedded call or put options. ASU 2016-06 clarifies the requirements for assessing whether contingent call or put options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. Entities performing the assessment under the guidance of ASU 2016-06 are required to assess the embedded call or put options solely in accordance with the four-step decision process. In addition, ASU 2016-06 clarifies what steps are required when assessing whether the economic characteristics and risks of call or put options are clearly and closely related to the economic characteristics and risks of their debt hosts. ASU 2016-06 is effective for financial statements issued for fiscal years beginning after December 15, 2016 and interim periods within those fiscal years using the modified retrospective method for existing debt instruments. The Company’s adoption of this standard did not have a material effect on its condensed consolidated financial statements.

Accounting Standards Issued, Not Adopted

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASC 2016-15”), which provides guidance on the classification of certain specific cash flow issues including debt prepayment or extinguishment costs, settlement of certain debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of certain insurance claims and distributions received from equity method investees. The standard requires the use of a retrospective approach to all periods presented, but may be applied prospectively if retrospective application would be impracticable. The guidance is effective for public entities for fiscal years beginning after December 15, 2017, and interim periods within those years, and early application is permitted. The Company is currently evaluating the impact of its pending adoption of ASU 2016-15 on the Company’s consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”), which applies to all leases. Under ASU 2016-02, a right-of-use asset and lease obligation will be recorded for all leases, whether operating or financing leases, while the statement of operations will reflect lease expense for operating leases and amortization and interest expense for financing leases. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018 and interim periods within those years, which is the year ended December 31, 2019 for the Company. Entities are required to use a modified retrospective approach of adoption for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. Full retrospective application is prohibited. The Company is evaluating the new guidance and the expected effect on the Company’s consolidated financial statements.

In June 2014, the FASB issued amended guidance, ASU No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), which is applicable to revenue recognition that will now be effective for the Company for the year ending December 31, 2018, as a result of the deferral of the effective date adopted by the FASB in July 2015. The new guidance must be adopted using either a full retrospective approach for all periods presented or a modified retrospective approach. Early adoption prior to the original adoption date of ASU 2014-09 is not permitted. The new guidance applies a more principles-based approach to revenue recognition. The Company currently anticipates adoption of the new standard effective January 1, 2018 under the modified retrospective method. The Company is analyzing the potential impact that ASU 2014-09 may have on its financial position and results of operations; however, the Company anticipates significant changes to its financial statement disclosures. As of September 30, 2017, the Company has completed its revenue stream analysis and advanced its assessment of the impact of ASU 2014-09 on its revenue-generating arrangements, including its product sales made as direct sales, sales to distributors, reagent rental agreements and its research arrangements. The Company is in the process of finalizing the quantitative impact the ASUs will have on the financial statements, as well as its plan for implementation. In addition, the Company continues to monitor additional changes, modifications, clarifications or interpretations undertaken by the FASB, which may impact its conclusions.

Fair Value Measurements

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

The Company measures the following financial assets at fair value on a recurring basis. There were no transfers between levels of the fair value hierarchy during any of the periods presented. The following tables set forth the Company’s financial assets carried at fair value categorized using the lowest level of input applicable to each financial instrument as of September 30, 2017 and December 31, 2016 (in thousands):

	Balance at September 30, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash	$	19,644	$	19,644	$	—	$	—
Money market funds		33,253		33,253		—		—
Restricted cash		260		260		—		—
Total	$	53,157	$	53,157	$	—	$	—

	Balance at December 31, 2016		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash	$	16,887	$	16,887	$	—	$	—
Money market funds		56,601		56,601		—		—
Restricted cash		260		260		—		—
Total	$	73,748	$	73,748	$	—	$	—

For certain financial instruments, including accounts payable and accrued expenses, the carrying amounts approximate their fair values as of September 30, 2017 and December 31, 2016 because of their short-term nature. At September 30, 2017 and December 31, 2016, the carrying value of the Company’s debt approximated fair value, which was determined using Level 3 inputs, using market quotes from brokers and is based on current rates offered for similar debt (Note 5).

- Definition

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

+ References + Details

Supplemental Balance Sheet Information

9 Months Ended

Sep. 30, 2017

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Supplemental Balance Sheet Information

4. Supplemental Balance Sheet Information

Inventories

Inventories are stated at the lower of cost or net realizable value on a first-in, first-out basis and are comprised of the following (in thousands):

	September 30, 2017		December 31, 2016
Raw materials	$	500	$	389
Work-in-process		476		351
Finished goods		278		63
Total inventories, net	$	1,254	$	803

Property and Equipment

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

	September 30, 2017			December 31, 2016
Office and computer equipment	$	409		$	409
Software		743			708
Laboratory equipment		4,094			4,516
Furniture		200			200
Manufacturing equipment		910			897
Manufacturing tooling and molds		160			154
T2-owned instruments and components		10,878			9,119
Leasehold improvements		3,378			3,353
Construction in progress		1,557			1,299
		22,329			20,655
Less accumulated depreciation and amortization		(8,475	)		(7,066	)
Property and equipment, net	$	13,854		$	13,589

Construction in progress is primarily comprised of equipment and leasehold improvement projects that have not been placed in service. T2-owned instruments and components is comprised of raw materials and work-in-process inventory that are expected to be used or used to produce T2-owned instruments, based on our business model and forecast, and completed instruments that will be used for internal research and development, clinical studies or reagent rental agreements with customers. Completed T2-owned instruments are placed in service once installation procedures are completed and are depreciated over five years. The Company has approximately $7.9 million and $5.7 million of T2-owned instruments installed and depreciating as of September 30, 2017 and December 31, 2016, respectively. Depreciation expense for T2-owned instruments placed at customer sites pursuant to reagent rental agreements is recorded as a component of cost of product revenue and totaled approximately $0.2 million and $0.2 million for the three months ended September 30, 2017 and 2016, respectively, and $0.7 million and $0.4 million for the nine months ended September 30, 2017 and 2016, respectively. Depreciation expense for T2-owned instruments used for internal research and development and clinical studies is recorded as a component of research and development expense.

Accrued Expenses

Accrued expenses consist of the following (in thousands):

	September 30, 2017		December 31, 2016
Accrued payroll and compensation	$	2,875	$	2,479
Accrued research and development expenses		1,038		846
Accrued professional services		987		884
Other accrued expenses		613		699
Total accrued expenses	$	5,513	$	4,908

Notes Payable

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Notes Payable

5. Notes Payable

Future principal payments on the notes payable are as follows (in thousands):

	September 30, 2017			December 31, 2016
Term loan agreement, net of deferred issuance costs of $2.5 million and $3.0 million, respectively	$	38,695		$	37,031
Equipment lease credit facility, net of deferred issuance cost of $29 thousand and $45 thousand, respectively		2,810			3,742
Total notes payable		41,505			40,773
Less: current portion of notes payable		(1,416	)		(1,269	)
Notes payable, net of current portion	$	40,089		$	39,504

Term Loan Agreement

In December 2016, the Company entered into a Term Loan Agreement (the “Term Loan Agreement”) with CRG Servicing LLC (“CRG”). The Company initially borrowed $40.0 million pursuant to the Term Loan Agreement and may borrow up to an additional $10.0 million at any time through and including July 27, 2018, provided that, among other conditions, the Company receives 510(k) clearance for the marketing of T2Bacteria by the FDA on or before April 30, 2018 (the “Approval Milestone”). The Term Loan Agreement has a six-year term with three years (through December 30, 2019) of interest-only payments, which period shall be extended to four years (through December 30, 2020) if the Company achieves the Approval Milestone, after which quarterly principal and interest payments will be due through the December 30, 2022 maturity date. Interest on the amounts borrowed under the Term Loan Agreement accrues at an annual fixed rate of (a) prior to the Approval Milestone, 12.5%, 4.0% of which may be deferred during the interest-only period by adding such amount to the aggregate principal loan amount and (b) following the Approval Milestone, 11.5%, 3.5% of which may be deferred during the interest-only period by adding such amount to the aggregate principal loan amount. In addition, if the Company achieves certain financial performance metrics, the loan will convert to interest-only until the December 30, 2022 maturity, at which time all unpaid principal and accrued unpaid interest will be due and payable. The Company is required to pay CRG a financing fee based on the loan principal amount drawn. The Company is also required to pay a final payment fee of 8.0% of the principal outstanding upon repayment, which is being accreted over the term of the debt as additional interest expenses.

The Company may prepay all or a portion of the outstanding principal and accrued unpaid interest under the Term Loan Agreement at any time upon prior notice subject to a prepayment fee during the first five years of the term and no prepayment fee thereafter. As security for its obligations under the Term Loan Agreement the Company entered into a security agreement with CRG whereby the Company granted a lien on substantially all of its assets, including intellectual property. The Term Loan Agreement also contains customary affirmative and negative covenants for a credit facility of this size and type. The Term Loan Agreement also requires the Company to achieve certain annual revenue targets, whereby the Company is required to pay double the amount of any shortfall as an acceleration of principal payments. The revenue target for fiscal 2017 is $5.0 million on this provision. The Term Loan Agreement includes a subjective acceleration clause whereby an event of default, including a material adverse change in the business, operations, or conditions (financial or otherwise), could result in the acceleration of the obligations under the Term Loan Agreement. Under certain circumstances, a default interest rate of an additional 4.0% per annum will apply at the election of CRG on all outstanding obligations during the occurrence and continuance of an event of default. CRG has not exercised its right under this clause, as there have been no such events. The Company believes the likelihood of CRG exercising this right is remote.

The Company assessed the terms and features of the Term Loan Agreement in order to identify any potential embedded features that would require bifurcation or any beneficial conversion features. As part of this analysis, the Company assessed the economic characteristics and risks of the Term Loan Agreement, including put and call features. The Company determined that the features of the Term Loan Agreement are either clearly and closely associated with a debt host and do not require bifurcation as a derivative liability, or the fair value of the feature is immaterial. Included in these features are principal payment acceleration clauses triggered by a developmental milestone. Should the Company’s assessment of this milestone change, there could be a non-cash charge in operations. The Company will continue to reassess the features to determine if they require separate accounting on a quarterly basis.

In December 2016, pursuant to the Term Loan Agreement, the Company made an initial draw of $39.2 million, net of financing fees. The Company used approximately $28.0 million of the initial proceeds to repay approximately $27.5 million of outstanding debt pursuant to the Loan and Security Agreement and to repay approximately $0.5 million of outstanding debt pursuant to the Promissory Note. Upon the repayment of all amounts owed by the Company under these agreements, all commitments were terminated and all security interests granted by the Company were released.

In connection with the Term Loan Agreement entered into in December 2016, the Company issued to CRG four separate warrants to purchase a total of 528,958 shares of the Company’s common stock. The warrants are exercisable any time prior to December 30, 2026 at a price of $8.06 per share, with typical provisions for termination upon a change of control or a sale of all or substantially all of the assets of the Company. The warrants are classified within shareholders’ equity, and the proceeds were allocated between the debt and warrants based on their relative fair value. The fair value of the warrants was determined by the Black Scholes Merton option pricing model. The fair value of the warrants at issuance on December 30, 2016 was $1.8 million.

Equipment Lease Credit Facility

In October 2015, the Company signed a $10.0 million Credit Facility with Essex Capital Corporation (the “Lessor”) to fund capital equipment needs. As one of the conditions of the Term Loan Agreement, the Credit Facility is capped at a maximum of $5.0 million. Under the Credit Facility, Essex will fund capital equipment purchases presented by the Company. The Company will repay the amounts borrowed in 36 equal monthly installments from the date of the amount funded. At the end of the 36 month lease term, the Company has the option to (a) repurchase the leased equipment at the lesser of fair market value or 10% of the original equipment value, (b) extend the applicable lease for a specified period of time, which will not be less than one year, or (c) return the leased equipment to the Lessor.

In April 2016 and June 2016, the Company completed the first two draws under the Credit Facility, of $2.1 million and $2.5 million, respectively. The Company will make monthly payments of $67,000 under the first draw and $79,000 under the second draw. The borrowings under the Credit Facility are treated as capital leases. The amortization of the assets conveyed under the Credit Facility is included as a component of depreciation expense.

Stockholders' Equity	9 Months Ended
Stockholders' Equity	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	6. Stockholders’ Equity Private Investment in Public Equity Financing On September 21, 2016, Canon U.S.A., Inc. (“Canon”) became a related party when the Company sold 6,055,341 shares of its common stock (the “Canon Shares”) to Canon at $6.56 per share, the closing price on this date, for an aggregate cash purchase price of $39.7 million. As of September 21, 2016, the Canon Shares represented 19.9% of the outstanding shares of common stock of the Company. In connection with the sale of the Canon Shares, the Company agreed to grant Canon certain board designation rights, including the right to initially appoint a Class I director to the Company’s board of directors. On March 20, 2017, the Company filed with the Securities and Exchange Commission (the “SEC”) a registration statement on Form S-3 for purposes of registering the resale of the Canon Shares with the SEC. On September 15, 2017, the company sold 5,031,250 shares of its common stock in a CMPO at $4.00 per share, for an aggregate gross cash purchase price of $20.1 million, or proceeds of $18.8 million after underwriters discount and expenses.

Stock-Based Compensation

9 Months Ended

Sep. 30, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

7. Stock-Based Compensation

Stock Incentive Plans

2006 Stock Incentive Plan

The Company’s 2006 Employee, Director and Consultant Stock Option Plan (“2006 Plan”) was established for granting stock incentive awards to directors, officers, employees and consultants of the Company. Upon closing of the Company’s IPO in August 2014, the Company ceased granting stock incentive awards under the 2006 Plan. The 2006 Plan provided for the grant of incentive and non-qualified stock options and restricted stock grants as determined by the Company’s board of directors. Under the 2006 Plan, stock options were generally granted with exercise prices equal to or greater than the fair value of the common stock as determined by the board of directors, expired no later than 10 years from the date of grant, and vest over various periods not exceeding 4 years.

2014 Stock Incentive Plan

The Company’s 2014 Incentive Award Plan (“2014 Plan”, and together with the 2006 Plan, the “Stock Incentive Plans”), provides for the issuance of shares of common stock in the form of stock options, awards of restricted stock, awards of restricted stock units, performance awards, dividend equivalent awards, stock payment awards and stock appreciation rights to directors, officers, employees and consultants of the Company. Since the establishment of the 2014 Plan, the Company has only granted stock options and restricted stock units. Generally, stock options are granted with exercise prices equal to or greater than the fair value of the common stock on the date of grant, expire no later than 10 years from the date of grant, and vest over various periods not exceeding 4 years.

The number of shares reserved for future issuance under the 2014 Plan is the sum of (1) 823,529 shares, (2) any shares that were granted under the 2006 Plan which are forfeited, lapsed unexercised or are settled in cash subsequent to the effective date of the 2014 Plan and (3) an annual increase on the first day of each calendar year beginning January 1, 2015 and ending on January 1, 2024, equal to the lesser of (A) 4% of the shares outstanding (on an as-converted basis) on the final day of the immediately preceding calendar year, and (B) such smaller number of shares determined by the Company’s Board of Directors. As of September 30, 2017 there were 979,124 shares available for future grant under the 2014 Plan.

Stock Options

During the nine months ended September 30, 2017 and 2016, the Company granted stock options with an aggregate fair value of $2.5 million and $6.6 million, respectively, which are being amortized into compensation expense over the vesting period of the stock options as the services are being provided.

The following is a summary of stock option activity under the Plans (in thousands, except share and per share amounts):

	Number of Shares			Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term (In years)		Aggregate Intrinsic Value
Outstanding at December 31,2016		4,042,627		$	8.20		7.05	$	4,091
Granted		807,450			5.18		6.00
Exercised		(194,783	)		2.34				502
Forfeited		(554,867	)		9.17
Cancelled		(267,127	)		12.56
Outstanding at September 30, 2017		3,833,300			7.42		6.67		1,040
Exercisable at September 30, 2017		2,440,070			7.24		5.57		976
Vested or expected to vest at September 30, 2017		3,600,971			7.35		5.77		1,024

Included in the stock options outstanding as of December 31, 2016 are 166,066 options to purchase common stock granted to certain executive officers of the Company that vest upon the achievement of certain performance conditions, which include the attainment of specified operating result and regulatory targets, by December 31, 2017, of which 20,000 options to purchase common stock upon the achievement of certain performance conditions were forfeited during the year ended December 31, 2016. There are 146,066 performance based stock options outstanding at September 30, 2017 and December 31, 2016. The Company will continually evaluate the probability of achievement of each performance condition and will commence recognition of stock-based compensation expense on these awards in the period the achievement of each performance condition is deemed probable, including a catch-up adjustment from the grant date.

The weighted-average grant date fair values of stock options granted in the nine month periods ended September 30, 2017 and 2016 were $3.04 per share and $4.76 per share, respectively, and were calculated using the following estimated assumptions:

	Nine Months Ended
	September 30,
	2017			2016
Weighted-average risk-free interest rate		1.98	%		1.42	%
Expected dividend yield		—	%		—	%
Expected volatility		63	%		61	%
Expected terms	6.0 years			6.0 years

The total fair values of stock options that vested during the nine months ended September 30, 2017 and 2016 were $3.5 million and $3.7 million, respectively.

As of September 30, 2017, there was $5.2 million of total unrecognized compensation cost related to unvested stock options granted under the Stock Incentive Plans, including the unrecognized compensation expense of stock options with performance conditions deemed probable of vesting. Total unrecognized compensation cost will be adjusted for future changes in the estimated forfeiture rate. The Company expects to recognize that cost over a remaining weighted-average period of 2.24 years as of September 30, 2017.

Restricted Stock Units

During the nine months ended September 30, 2017, the Company awarded shares of restricted stock units to certain employees and directors at no cost to them, which cannot be sold, assigned, transferred or pledged during the restriction period. The restricted stock and restricted stock units vest through the passage of time, assuming continued employment. Restricted stock units are not included in issued and outstanding common stock until the shares are vested and released. The fair value of the award at the time of the grant is expensed on a straight line basis. The granted restricted stock units had an aggregate fair value of $2.9 million, which are being amortized into compensation expense over the vesting period of the options as the services are being provided.

The following is a summary of restricted stock unit activity under the 2014 Plan (in thousands, except share and per share amounts):

	Number of Shares			Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2016		272,195			5.83
Granted		552,925			5.17
Vested		—			—
Forfeited		(74,800	)		5.87
Canceled		—			—
Nonvested at September 30, 2017		750,320			5.34

There was no vesting of restricted stock units during the nine months ended September 30, 2017. As of September 30, 2017, there was $2.6 million of total unrecognized compensation cost related to unvested restricted stock units granted under the Stock Incentive Plans. Total unrecognized compensation cost will be adjusted for future forfeitures. The Company expects to recognize that cost over a remaining weighted-average period of 1.7 years as of September 30, 2017.

Stock-Based Compensation Expense

The following table summarizes the stock-based compensation expense resulting from awards granted under stock incentive plans, including the 2014 ESPP, that was recorded in the Company’s results of operations for the periods presented (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Cost of product revenue	$	18	$	27	$	87	$	86
Research and development		340		292		1,047		902
Selling, general and administrative		862		779		2,555		2,572
Total stock-based compensation expense	$	1,220	$	1,098	$	3,689	$	3,560

For the three months ended September 30, 2017 and 2016, $33,000 and $32,000 of stock-based compensation expenses were capitalized as part of inventory or T2Dx instruments and components, respectively. For the nine months ended September 30, 2017 and 2016, $117,000 and $99,000 of stock-based compensation expenses were capitalized as part of inventory or T2Dx instruments and components, respectively.

Warrants	9 Months Ended
Warrants	Sep. 30, 2017
Text Block [Abstract]
Warrants	8. Warrants In connection with the Term Loan Agreement entered into in December 2016, the Company issued to CRG four separate warrants to purchase a total of 528,958 shares of the Company’s common stock. The warrants are exercisable any time prior to December 30, 2026 at a price of $8.06 per share, with typical provisions for termination upon a change of control or a sale of all or substantially all of the assets of the Company. The warrants are classified within shareholders’ equity, and the proceeds were allocated between the debt and warrants based on their relative fair value. The fair value of the warrants was determined by the Black-Scholes-Merton option pricing model. The fair value of the warrants at issuance on December 30, 2016 was $1.8 million.

Net Loss Per Share

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Net Loss Per Share

9. Net Loss Per Share

The following shares were excluded from the calculation of diluted net loss per share applicable to common stockholders, prior to the application of the treasury stock method, because their effect would have been anti-dilutive for the periods presented:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Options to purchase common shares		3,833,300		4,263,094		3,833,300		4,263,094
Restricted stock units		750,320		—		750,320		—
Warrants to purchase common stock		528,958		—		528,958		—
Total		5,112,578		4,263,094		5,112,578		4,263,094

Co-Development Agreements	9 Months Ended
Co-Development Agreements	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Co-Development Agreements	10. Co-Development Agreements Canon US Life Sciences On September 21, 2016, Canon became a related party when the Company sold the Canon Shares for an aggregate cash purchase price of $39.7 million, which represented 19.9% of the outstanding shares of common stock of the Company. On February 3, 2015, the Company entered into a Co-Development Partnership Agreement (the “Co-Development Agreement”) with Canon U.S. Life Sciences, Inc. (“Canon US Life Sciences”) to develop a diagnostic test panel to rapidly detect Lyme disease. Under the terms of the Co-Development Agreement, the Company received an upfront payment of $2.0 million from Canon US Life Sciences, and the agreement includes an additional $6.5 million of consideration upon achieving certain development and regulatory milestones for total aggregate payments of up to $8.5 million. In October 2015, the Company achieved a specified technical requirement and received $1.5 million related to the achievement of the milestone. The Company is eligible to receive an additional $5.0 million under the arrangement, in two milestone payments of $2.0 million and $3.0 million, related to the achievement of additional development and regulatory milestones. All payments under the Co-Development Agreement are non-refundable once received. The Company will retain exclusive worldwide commercialization rights of any products developed under the Co-Development Agreement, including sales, marketing and distribution and Canon US Life Sciences will not receive any commercial rights and will be entitled to only receive royalty payments on the sales of all products developed under the Co-Development Agreement. Either party may terminate the Co-Development Agreement upon the occurrence of a material breach by the other party (subject to a cure period). The Company evaluated the deliverables under the Co-Development Agreement and determined that the Co-Development Agreement included one unit of accounting, the research and development services, as the joint research and development committee deliverable was deemed to be de minimis. The Company is recognizing revenue for research and development services as a component of research revenue in the condensed consolidated financial statements as the services are delivered using the proportional performance method of accounting, limited to payments earned. Costs incurred to deliver the services under the Co-Development Agreement are recorded as research and development expense in the condensed consolidated financial statements. The Company recorded revenue of $0.0 and $0.4 million during the three months ended September 30, 2017 and September 30, 2016, respectively, and recorded revenue of $0.3 million and $1.5 million during the nine months ended September 30, 2017 and 2016, under the Co-Development Agreement, and expects to record revenue over the next two years, provided development milestones are achieved. Allergan Sales, LLC On November 1, 2016, the Company entered into a Co-Development, Collaboration and Co-Marketing Agreement (the “Allergan Agreement”) with Allergan Sales, LLC (“Allergan Sales”) to develop (1) a direct detection diagnostic test panel that adds one additional bacteria species to the existing T2Bacteria product candidate (the “T2Bacteria II Panel”), and (2) a direct detection diagnostic test panel for testing drug resistance directly in whole blood (the “T2GNR Panel” and, together with the T2Bacteria II Panel, the “Developed Products”). In addition, both the Company and Allergan Sales will participate in a joint research and development committee and Allergan Sales will receive the right to cooperatively market the T2Candida, T2Bacteria, and the Developed Products under the Allergan Agreement to certain agreed-upon customers. On June 1, 2017 the Company and Allergan Sales entered into an Amendment to the Allergan Agreement which primarily modified the project plan to combine the T2Bacteria II Panel and T2GNR Panel into one test panel. Under the terms of the Allergan Agreement, the Company received an upfront payment of $2.0 million from Allergan Sales and will receive additional milestone payments upon achieving certain developmental milestones for total aggregate payments of up to $4.0 million. All payments under the Allergan Agreement are non-refundable once received. The Company will retain exclusive worldwide commercialization rights of any products developed under the Allergan Agreement, including distribution, subject to Allergan Sales’ right to co-market the Developed Products. Allergan Sales, at its election, may co-market T2Candida, T2Bacteria and the Developed Products worldwide to certain agreed-upon customers and will receive royalty based on its sales for a period of time. The Company evaluated the deliverables under the Allergan Agreement and determined that the Allergan Agreement included two units of accounting, the research and development services for the T2Bacteria II Panel and the research and development services for the T2GNR Panel, as the joint research and development committee and right to cooperatively market deliverables were deemed to be de minimus. The Company is recognizing revenue for research and development services as a component of research revenue in the consolidated financial statements as the services are delivered using the proportional performance method of accounting, limited to payments earned. Costs incurred to deliver the services under the Allergan Agreement are recorded as research and development expense in the consolidated financial statements. The Company recorded revenue of $0.4 million and $0.6 million for the three and nine months ended September 30, 2017, respectively, under the Allergan Agreement and expects to record revenue over the next two years, provided development and regulatory milestones are achieved.

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	11. Subsequent Events. None

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2017

Accounting Policies [Abstract]

Basis of Presentation

Unaudited Interim Financial Information

Persuasive evidence of an arrangement exists

ii.

Delivery has occurred or services have been rendered

iii.

The seller’s price to the buyer is fixed or determinable

iv.

Collectability is reasonably assured

If any of the above criteria have not been met, the Company defers revenue until such time each of the criteria have been satisfied.

The Company does not offer rights of return for instruments or consumable diagnostic tests.

Product Recall

Cost of Product Revenue

Research and Development Costs

Recent Accounting Standards

Accounting Standards Adopted

Accounting Standards Issued, Not Adopted

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities at Fair value on a Recurring Basis

	Balance at September 30, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash	$	19,644	$	19,644	$	—	$	—
Money market funds		33,253		33,253		—		—
Restricted cash		260		260		—		—
Total	$	53,157	$	53,157	$	—	$	—

	Balance at December 31, 2016		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash	$	16,887	$	16,887	$	—	$	—
Money market funds		56,601		56,601		—		—
Restricted cash		260		260		—		—
Total	$	73,748	$	73,748	$	—	$	—

Supplemental Balance Sheet Information (Tables)

9 Months Ended

Sep. 30, 2017

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Schedule of Inventory

Inventories are stated at the lower of cost or net realizable value on a first-in, first-out basis and are comprised of the following (in thousands):

	September 30, 2017		December 31, 2016
Raw materials	$	500	$	389
Work-in-process		476		351
Finished goods		278		63
Total inventories, net	$	1,254	$	803

Schedule of Property and Equipment

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

	September 30, 2017			December 31, 2016
Office and computer equipment	$	409		$	409
Software		743			708
Laboratory equipment		4,094			4,516
Furniture		200			200
Manufacturing equipment		910			897
Manufacturing tooling and molds		160			154
T2-owned instruments and components		10,878			9,119
Leasehold improvements		3,378			3,353
Construction in progress		1,557			1,299
		22,329			20,655
Less accumulated depreciation and amortization		(8,475	)		(7,066	)
Property and equipment, net	$	13,854		$	13,589

Components of Accrued Expenses

Accrued expenses consist of the following (in thousands):

	September 30, 2017		December 31, 2016
Accrued payroll and compensation	$	2,875	$	2,479
Accrued research and development expenses		1,038		846
Accrued professional services		987		884
Other accrued expenses		613		699
Total accrued expenses	$	5,513	$	4,908

Notes Payable (Tables)

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Schedule of Debt

Future principal payments on the notes payable are as follows (in thousands):

	September 30, 2017			December 31, 2016
Term loan agreement, net of deferred issuance costs of $2.5 million and $3.0 million, respectively	$	38,695		$	37,031
Equipment lease credit facility, net of deferred issuance cost of $29 thousand and $45 thousand, respectively		2,810			3,742
Total notes payable		41,505			40,773
Less: current portion of notes payable		(1,416	)		(1,269	)
Notes payable, net of current portion	$	40,089		$	39,504

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following is a summary of stock option activity under the Plans (in thousands, except share and per share amounts):

	Number of Shares			Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term (In years)		Aggregate Intrinsic Value
Outstanding at December 31,2016		4,042,627		$	8.20		7.05	$	4,091
Granted		807,450			5.18		6.00
Exercised		(194,783	)		2.34				502
Forfeited		(554,867	)		9.17
Cancelled		(267,127	)		12.56
Outstanding at September 30, 2017		3,833,300			7.42		6.67		1,040
Exercisable at September 30, 2017		2,440,070			7.24		5.57		976
Vested or expected to vest at September 30, 2017		3,600,971			7.35		5.77		1,024

Schedule of Estimated Assumptions Used to Calculate Weighted-Average Grant Date Fair Value of Options Granted

	Nine Months Ended
	September 30,
	2017			2016
Weighted-average risk-free interest rate		1.98	%		1.42	%
Expected dividend yield		—	%		—	%
Expected volatility		63	%		61	%
Expected terms	6.0 years			6.0 years

Schedule of Nonvested Restricted Stock Units Activity

The following is a summary of restricted stock unit activity under the 2014 Plan (in thousands, except share and per share amounts):

	Number of Shares			Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2016		272,195			5.83
Granted		552,925			5.17
Vested		—			—
Forfeited		(74,800	)		5.87
Canceled		—			—
Nonvested at September 30, 2017		750,320			5.34

Summary of Stock-Based Compensation Expense for Stock Options Granted that was Recorded in the Company's Results of Operations

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Cost of product revenue	$	18	$	27	$	87	$	86
Research and development		340		292		1,047		902
Selling, general and administrative		862		779		2,555		2,572
Total stock-based compensation expense	$	1,220	$	1,098	$	3,689	$	3,560

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Options to purchase common shares		3,833,300		4,263,094		3,833,300		4,263,094
Restricted stock units		750,320		—		750,320		—
Warrants to purchase common stock		528,958		—		528,958		—
Total		5,112,578		4,263,094		5,112,578		4,263,094

Nature of Business - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Debt Instrument
Cash and cash equivalents	$ 52,897	$ 73,488	$ 75,111	$ 73,662
Accumulated deficit	(247,923)	$ (203,689)
Loan and Security Agreement [Member]
Debt Instrument
Remaining borrowing capacity	$ 10,000

Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Segment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Product Information [Line Items]
Number of operating segments \| Segment			1
Deferred revenue	$ 2,076,000		$ 2,076,000		$ 2,445,000
Costs of product revenue	2,106,000	$ 1,894,000	5,722,000	$ 4,701,000
Accounting Standards Update 201609 Excess Tax Benefit Component [Member] \| Retained Earnings [Member]
Product Information [Line Items]
Cumulative effect of new accounting principle in period of adoption	1,200,000		$ 1,200,000
T2 Dx [Member]
Product Information [Line Items]
Maintenance Services period (in years)			1 year
Additional period for Maintenance Service option (in years)			1 year
T2 Candida [Member]
Product Information [Line Items]
Deferred revenue	20,000	$ 149,000	$ 20,000	149,000
Costs of product revenue				$ 41,000
Remaining warranty reserve	$ 2,000		$ 2,000

Fair Value Measurements - Schedule of Financial Assets and Liabilities at Fair value on a Recurring Basis (Detail) - Estimate of Fair Value Measurement [Member] - Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Restricted cash	$ 260	$ 260
Total assets	53,157	73,748
Cash [Member]
Assets:
Cash	19,644	16,887
Money Market Funds [Member]
Assets:
Cash	33,253	56,601
Level 1 [Member]
Assets:
Restricted cash	260	260
Total assets	53,157	73,748
Level 1 [Member] \| Cash [Member]
Assets:
Cash	19,644	16,887
Level 1 [Member] \| Money Market Funds [Member]
Assets:
Cash	$ 33,253	$ 56,601

Supplemental Balance Sheet Information - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Balance Sheet Related Disclosures [Abstract]
Raw materials	$ 500	$ 389
Work-in-process	476	351
Finished goods	278	63
Total inventories, net	$ 1,254	$ 803

Supplemental Balance Sheet Information - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 22,329	$ 20,655
Less accumulated depreciation and amortization	(8,475)	(7,066)
Property and equipment, net	13,854	13,589
Office and Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	409	409
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	743	708
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,094	4,516
Furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	200	200
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	910	897
Manufacturing Tooling and Molds [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	160	154
T2-Owned Instruments and Components [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10,878	9,119
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,378	3,353
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,557	$ 1,299

Supplemental Balance Sheet Information - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Supplemental Balance Sheet Information [Line Items]
Property and equipment, gross	$ 22,329		$ 22,329		$ 20,655
T2 Owned Instruments in Service [Member]
Supplemental Balance Sheet Information [Line Items]
Property and equipment, gross	7,900		$ 7,900		$ 5,700
Estimated useful lives (in years)			5 years
Depreciation expense recorded as a component of cost of product revenue	$ 200	$ 200	$ 700	$ 400

Supplemental Balance Sheet Information - Components of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accrued Liabilities Current [Abstract]
Accrued payroll and compensation	$ 2,875	$ 2,479
Accrued research and development expenses	1,038	846
Accrued professional services	987	884
Other accrued expenses	613	699
Total accrued expenses	$ 5,513	$ 4,908

Notes Payable - Schedule of Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument
Total notes payable	$ 41,505	$ 40,773
Less: current portion of notes payable	(1,416)	(1,269)
Notes payable, net of current portion	40,089	39,504
Medium-term Notes [Member] \| Term Loan Agreement [Member]
Debt Instrument
Total notes payable	38,695	37,031
Line of Credit [Member] \| Equipment Lease Credit Facility [Member]
Debt Instrument
Total notes payable	$ 2,810	$ 3,742

Notes Payable - Schedule of Debt (Parenthetical) (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Term Loan Agreement [Member] \| Medium-term Notes [Member]
Debt Instrument
Deferred issuance costs	$ 2,500	$ 3,000
Equipment Lease Credit Facility [Member] \| Line of Credit [Member]
Debt Instrument
Deferred issuance costs	$ 29	$ 45

Notes Payable - Term Loan Agreement - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended	9 Months Ended		12 Months Ended
	Dec. 31, 2016 USD ($) Warrant $ / shares shares	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument
Proceeds from issuance of note payable, net			$ 4,593
Repayments of note payable		$ 898	$ 2,481
Common Stock [Member]
Debt Instrument
Number of warrants \| Warrant	4
Number of shares issuable for warrants outstanding (in shares) \| shares	528,958
Exercise price of warrants \| $ / shares	$ 8.06
Fair market value of warrants	$ 1,800
Loan and Security Agreement [Member]
Debt Instrument
Repayments of note payable	27,500
Promissory Note [Member]
Debt Instrument
Repayments of note payable	500
CRG Servicing LLC [Member] \| Term Loan Agreement [Member]
Debt Instrument
Proceeds from issuance of long-term debt	40,000
Line of credit, additional borrowing capacity	$ 10,000
Debt term (in years)	6 years
Debt instrument, term of interest-only payments (in years)	3 years
Debt instrument, extended term interest only payments (in years)	4 years
Final fee as a percentage of the principal outstanding (as a percent)	8.00%
Debt instrument, prepayment fee term (in years)	5 years
Additional interest rate, event of default (as a percent)	4.00%
Proceeds from issuance of note payable, net	$ 39,200
Portion of proceeds used for debt repayment	$ 28,000
CRG Servicing LLC [Member] \| Term Loan Agreement [Member] \| Scenario Forecast [Member]
Debt Instrument
Target revenues				$ 5,000
CRG Servicing LLC [Member] \| Term Loan Agreement [Member] \| Prior to Approval Milestone [Member]
Debt Instrument
Annual fixed rate (as a percent)	12.50%
Deferred interest rate (as a percent)	4.00%
CRG Servicing LLC [Member] \| Term Loan Agreement [Member] \| Following Approval Milestone [Member]
Debt Instrument
Annual fixed rate (as a percent)	11.50%
Deferred interest rate (as a percent)	3.50%

Notes Payable - Equipment Lease Credit Facility - Additional Information (Detail) - Capital Lease Obligations [Member]	1 Months Ended
	Jun. 30, 2016 USD ($) Draw	Apr. 30, 2016 USD ($)	Oct. 31, 2015 USD ($)
Debt Instrument
Initial borrowing capacity			$ 10,000,000
Maximum borrowings available (up to)			$ 5,000,000
Debt term (in months)			36 months
Repurchase price as percentage of original equipment value that the equipment under lease may be repurchased by lessee			10.00%
Minimum lease period to extend lease (in years)			1 year
Amount of draw	$ 2,500,000	$ 2,100,000
Amount of monthly payment	$ 79,000,000	$ 67,000,000
Number of draws \| Draw	2

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			9 Months Ended
	Sep. 15, 2017	Sep. 21, 2016	Sep. 30, 2016
Class of Stock [Line Items]
Proceeds from private investment in public equity			$ 39,723
Private Placement [Member]
Class of Stock [Line Items]
Number of shares sold		6,055,341
Sale price of stock (in dollars per share)		$ 6.56
Proceeds from private investment in public equity		$ 39,700
Percentage of common shares outstanding (as a percentage)		19.90%
CMPO [Member]
Class of Stock [Line Items]
Number of shares sold	5,031,250
Sale price of stock (in dollars per share)	$ 4.00
Proceeds from private investment in public equity	$ 20,100
Proceeds from private investment in public equity after underwriters discount and expenses	$ 18,800

Stock-Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Share-Based Compensation
Fair value of vested stock options			$ 3,500,000	$ 3,700,000
Unrecognized compensation cost related to unvested stock options	$ 5,200,000		$ 5,200,000
Weighted-average period			2 years 2 months 27 days
Stock-based compensation expense	1,220,000	$ 1,098,000	$ 3,689,000	3,560,000
T2Dx Instruments and Components [Member]
Share-Based Compensation
Stock-based compensation expense	$ 33,000	$ 32,000	$ 117,000	99,000
Performance-based awards [Member]
Share-Based Compensation
Outstanding, end of the period	146,066		146,066		146,066
Performance-based awards [Member] \| Executive Officer [Member]
Share-Based Compensation
Outstanding, end of the period					166,066
Forfeited performance stock based options					20,000
Restricted Stock Units [Member]
Share-Based Compensation
Unrecognized compensation cost related to unvested stock options	$ 2,600,000		$ 2,600,000
Weighted-average period			1 year 8 months 13 days
Restricted stock units, vested			0
2014 Stock Option Plan [Member] \| Stock Options [Member]
Share-Based Compensation
Shares available for future issuance under stock incentive plan	823,529		823,529
Percentage of common shares outstanding	4.00%		4.00%
Shares available for grant	979,124		979,124
2006 and 2014 Stock Option Plans [Member] \| Stock Options [Member]
Share-Based Compensation
Aggregate fair value of options granted			$ 2,500,000	$ 6,600,000
2006 and 2014 Stock Option Plans [Member] \| Stock Options [Member]
Share-Based Compensation
Outstanding, end of the period	3,833,300		3,833,300		4,042,627
Forfeited performance stock based options			554,867
Weighted average fair value of options granted			$ 3.04	$ 4.76
2006 and 2014 Stock Option Plans [Member] \| Restricted Stock Units [Member]
Share-Based Compensation
Aggregate fair value of options granted			$ 2,900,000
Maximum [Member] \| 2006 Stock Option Plan [Member] \| Stock Options [Member]
Share-Based Compensation
Expiration period			10 years
Vesting period			4 years
Maximum [Member] \| 2014 Stock Option Plan [Member] \| Stock Options [Member]
Share-Based Compensation
Expiration period			10 years
Vesting period			4 years

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - 2006 and 2014 Stock Option Plans [Member] - Stock Options [Member] - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Share-Based Compensation
Number of Shares Outstanding, beginning of the period	4,042,627
Number of Shares, Granted	807,450
Number of Shares, Exercised	(194,783)
Number of Shares, Forfeited	(554,867)
Number of Shares, Cancelled	(267,127)
Number of Shares Outstanding, end of the period	3,833,300	4,042,627
Number of Shares, Exercisable	2,440,070
Number of Shares, Vested or expected to vest	3,600,971
Weighted-Average Exercise Price Per Share Outstanding, beginning of the period	$ 8.20
Weighted-Average Exercise Price Per Share, Granted	5.18
Weighted-Average Exercise Price Per Share, Exercised	2.34
Weighted-Average Exercise Price Per Share, Forfeited	9.17
Weighted-Average Exercise Price Per Share, Cancelled	12.56
Weighted-Average Exercise Price Per Share Outstanding, end of the period	7.42	$ 8.20
Weighted-Average Exercise Price Per Share, Exercisable	7.24
Weighted-Average Exercise Price Per Share, Vested or expected to vest	$ 7.35
Weighted-Average Remaining Contractual Term, Outstanding	6 years 8 months 2 days	7 years 18 days
Weighted-Average Remaining Contractual Term, Granted	6 years
Weighted-Average Remaining Contractual Term, Exercisable	5 years 6 months 25 days
Weighted-Average Remaining Contractual Term, Vested or expected to vest	5 years 9 months 7 days
Aggregate Intrinsic Value, Outstanding, beginning of the period	$ 4,091
Aggregate Intrinsic Value, Exercised	502
Aggregate Intrinsic Value Outstanding, end of the period	1,040	$ 4,091
Aggregate Intrinsic Value, Exercisable	976
Aggregate Intrinsic Value, Vested or expected to vest	$ 1,024

Stock-Based Compensation - Schedule of Estimated Assumptions Used to Calculate Weighted-Average Grant Date Fair Value of Options Granted (Detail) - Stock Options [Member] - 2006 and 2014 Stock Option Plans [Member]	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share-Based Compensation
Weighted-average risk-free interest rate	1.98%	1.42%
Expected dividend yield	0.00%	0.00%
Expected volatility	63.00%	61.00%
Expected terms	6 years	6 years

Stock-Based Compensation - Schedule of Nonvested Restricted Stock Units Activity (Detail) - Restricted Stock Units [Member]	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Share-Based Compensation
Number of Shares, Unvested restricted shares at the beginning of the period \| shares	272,195
Number of Shares, Restricted shares granted \| shares	552,925
Number of Shares, Restricted shares vested \| shares	0
Number of Shares, Restricted shares forfeited \| shares	(74,800)
Number of Shares, Canceled \| shares	0
Number of Shares, Unvested restricted shares at the end of the period \| shares	750,320
Weighted-Average Grant Date Fair Value, Unvested restricted shares at the beginning of the period \| $ / shares	$ 5.83
Weighted-Average Grant Date Fair Value, Granted \| $ / shares	5.17
Weighted-Average Grant Date Fair Value, Vested \| $ / shares	0
Weighted-Average Grant Date Fair Value, Forfeited \| $ / shares	5.87
Weighted-Average Grant Date Fair Value, Canceled \| $ / shares	0
Weighted-Average Grant Date Fair Value, Unvested restricted shares at the end of the period \| $ / shares	$ 5.34

Stock-Based Compensation - Summary of Stock-Based Compensation Expense for Stock Options Granted that was Recorded in the Company's Results of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Stock-based compensation expense
Stock-based compensation expense	$ 1,220	$ 1,098	$ 3,689	$ 3,560
Cost of Product Revenue [Member]
Stock-based compensation expense
Stock-based compensation expense	18	27	87	86
Research and Development [Member]
Stock-based compensation expense
Stock-based compensation expense	340	292	1,047	902
Selling, General and Administrative [Member]
Stock-based compensation expense
Stock-based compensation expense	$ 862	$ 779	$ 2,555	$ 2,572

Warrants - Additional Information (Detail) - Common Stock [Member] $ / shares in Units, $ in Millions	1 Months Ended
	Dec. 31, 2016 USD ($) Warrant $ / shares shares
Class of Warrant or Right [Line Items]
Number of warrants \| Warrant	4
Number of shares issuable for warrants outstanding \| shares	528,958
Exercise price of warrants \| $ / shares	$ 8.06
Fair market value of warrants \| $	$ 1.8

Net Loss Per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities
Anti-dilutive securities excluded from the computation of diluted net loss per share	5,112,578	4,263,094	5,112,578	4,263,094
Options to Purchase Common Shares [Member]
Antidilutive Securities
Anti-dilutive securities excluded from the computation of diluted net loss per share	3,833,300	4,263,094	3,833,300	4,263,094
Restricted Stock Units [Member]
Antidilutive Securities
Anti-dilutive securities excluded from the computation of diluted net loss per share	750,320		750,320
Warrants to Purchase Common Stock [Member]
Antidilutive Securities
Anti-dilutive securities excluded from the computation of diluted net loss per share	528,958		528,958

Co-Development Agreements - Additional Information (Detail) $ in Thousands				1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 01, 2016 USD ($) specie	Sep. 21, 2016 USD ($)	Feb. 03, 2015 USD ($) Item	Oct. 31, 2015 USD ($)	Sep. 30, 2017 USD ($) Item	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Item	Sep. 30, 2016 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from sale of shares in related party								$ 39,723
Revenues					$ 1,108	$ 1,084	$ 3,005	3,171
Co Development Partnership Agreement [Member] \| Canon U.S. Life Sciences Inc [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment			$ 2,000
Additional consideration receivable upon achievement of certain development and regulatory milestones			6,500
Aggregate consideration receivable			$ 8,500
Proceeds received for achievement of milestone				$ 1,500
Additional consideration receivable upon achievement of additional development and regulatory milestones					$ 5,000		$ 5,000
Number of milestone payments \| Item					2		2
Additional consideration receivable upon achievement of development and regulatory milestones, payment one					$ 2,000		$ 2,000
Additional consideration receivable upon achievement of development and regulatory milestones, payment two					3,000		3,000
Number of units \| Item			1
Revenues					0	$ 400	300	$ 1,500
Co Development Partnership Agreement [Member] \| Allergan Sales [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment	$ 2,000
Aggregate consideration receivable	$ 4,000
Revenues					$ 400		$ 600
Number of additional bacteria species added to existing product candidate \| specie	1
Private Placement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from sale of shares in related party		$ 39,700
Percentage of outstanding shares at date of sale		19.90%