Immune Design 10-K 31 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 20, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	IMDZ
Entity Registrant Name	Immune Design Corp.
Entity Central Index Key	1437786
Current Fiscal Year End Date	-19
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		16,979,688
Entity Public Float			$0

Balance_Sheets

Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$75,354	$30,387
Accounts receivable	1,970	87
Inventory	25	17
Prepaid expenses	633	179
Total current assets	77,982	30,670
Property and equipment, net	401	295
Total assets	78,383	30,965
Current liabilities:
Accounts payable	6,903	866
Accrued liabilities	5,001	1,082
Deferred rent, current	43	27
Total current liabilities	11,947	1,975
Other noncurrent liabilities	90	94
Convertible preferred stock warrant liability	0	3,336
Commitments and contingencies
Convertible preferred stock, $0.001 par value per share; 10,000,000 and 12,882,593 shares authorized at December 31, 2014 and 2013, respectively; zero and 9,769,422 shares issued and outstanding at December 31, 2014 and 2013, respectively; liquidation preference of zero and $84,300 at December 31, 2014 and 2013, respectively	0	81,394
Stockholders’ equity (deficit):
Common stock, $0.001 par value per share; 100,000,000 and 15,045,871 shares authorized at December 31, 2014 and 2013, respectively; 16,878,817 and 369,460 shares issued and outstanding at December 31, 2014 and 2013, respectively	17	3
Additional paid-in capital	157,092	775
Accumulated deficit	-90,763	-56,612
Total stockholders’ equity (deficit)	66,346	-55,834
Total liabilities, convertible preferred stock and stockholders’ equity	$78,383	$30,965

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Convertible preferred stock
Par value per share (in USD per share)	$0.00	$0.00
Shares authorized	10,000,000	12,882,593
Shares issued	0	9,769,422
Shares outstanding	0	9,769,422
Liquidation preference	$0	$84,300
Common stock
Par value per share (in USD per share)	$0.00	$0.00
Shares authorized (in shares)	100,000,000	15,045,871
Shares issued (in shares)	16,878,817	369,460
Shares outstanding (in shares)	16,878,817	369,460

Statements_of_Operations

Statements of Operations (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Licensing revenue	$4,500	$729	$876
Product sales	881	870	1,877
Other, net	1,052	0	207
Total revenues	6,433	1,599	2,960
Operating expenses:
Cost of product sales	638	669	1,518
Research and development	22,746	11,554	8,604
General and administrative	12,927	4,433	3,713
Total operating expenses	36,311	16,656	13,835
Loss from operations	-29,878	-15,057	-10,875
Interest and other income	4	37	35
Change in fair value of convertible preferred stock warrant liability	-4,277	-955	0
Net loss attributable to common stockholders	($34,151)	($15,975)	($10,840)
Earnings Per Share
Basic and diluted net loss per share attributable to common stockholders (in USD per share)	($4.56)	($43.48)	($30.43)
Weighted Average Number of Shares Outstanding, Diluted
Weighted-average shares used to compute basic and diluted net loss per share attributable to common stockholders (in shares)	7,494,790	367,437	356,215

Statements_of_Convertible_Pref

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (USD $)	Total	Common stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Convertible preferred stock [Member]	Series B convertible preferred stock [Member]	Series C convertible preferred stock [Member]
In Thousands, except Share data, unless otherwise specified
Beginning balance, preferred stock at Dec. 31, 2011					$41,111
Beginning balance at Dec. 31, 2011	-29,535	3	259	-29,797
Beginning balance (in shares) at Dec. 31, 2011		349,051
Beginning balance, convertible preferred shares (in shares) at Dec. 31, 2011					4,688,191
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		11,910
Exercise of stock options	11		11
Stock-based compensation	244		244
Net loss	-10,840			-10,840
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred stock (in shares)						1,130,165
Issuance of convertible preferred stock						10,615
Ending balance, preferred stock at Dec. 31, 2012					51,726
Ending balance at Dec. 31, 2012	-40,120	3	514	-40,637
Ending balance (in shares) at Dec. 31, 2012		360,961
Ending balance, convertible preferred shares (in shares) at Dec. 31, 2012					5,818,356
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	8,499	8,499
Exercise of stock options	6		6
Stock-based compensation	255		255
Net loss	-15,975			-15,975
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred stock (in shares)							3,951,066
Issuance of convertible preferred stock							29,668
Ending balance, preferred stock at Dec. 31, 2013	81,394				81,394	33,804	29,668
Ending balance at Dec. 31, 2013	-55,834	3	775	-56,612
Ending balance (in shares) at Dec. 31, 2013	369,460	369,460
Ending balance, convertible preferred shares (in shares) at Dec. 31, 2013	9,769,422				9,769,422	3,616,529	3,951,066
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	20,508	20,508
Exercise of stock options	23		23
Stock-based compensation	1,344		1,344
Net loss	-34,151			-34,151
Number of common stock sold in IPO (in shares)		5,410,564
Stock issued during IPO	57,807	5	57,802
Conversion of preferred stock (in shares)		9,769,422			-9,769,422
Common shares issued for conversion of preferred shares	81,394	10	81,384		-81,394
Issuance of common stock upon exercise of warrants (in shares)		1,308,863
Issuance of common stock upon exercise of warrants	8,150	1	8,149
Conversion of preferred stock warrant liability	7,613		7,613
Reverse stock split true up		-2	2
Increase (Decrease) in Temporary Equity [Roll Forward]
Common shares issued for conversion of preferred shares	81,394	10	81,384		-81,394
Ending balance, preferred stock at Dec. 31, 2014	0				0
Ending balance at Dec. 31, 2014	$66,346	$17	$157,092	($90,763)
Ending balance (in shares) at Dec. 31, 2014	16,878,817	16,878,817
Ending balance, convertible preferred shares (in shares) at Dec. 31, 2014	0				0

Statements_of_Convertible_Pref1

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) Parenthetical (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Common stock [Member]
Share price (in USD per share)	$12
Stock issuance costs	$7,100
Warrant exercise price (in USD per share)	$12
Series C convertible preferred stock [Member]
Share price (in USD per share)		$8.18
Stock issuance costs		251
Series B convertible preferred stock [Member]
Share price (in USD per share)		$9.41	$9.41
Stock issuance costs			$10

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net loss	($34,151)	($15,975)	($10,840)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	238	407	548
Stock-based compensation expense	1,344	255	244
Revaluation of convertible preferred stock warrant liability	4,277	955	0
Other	0	94	23
Changes in operating assets and liabilities:
Accounts receivable	-1,883	426	-452
Inventory	-8	109	-252
Prepaid expenses	-454	8	152
Accounts payable	6,037	-213	504
Accrued liabilities	3,955	-453	623
Deferred rent	-24	89	-128
Net cash used in operating activities	-20,669	-14,298	-9,578
Investing activities
Purchases of property and equipment	-344	-175	-294
Proceeds from the sale of property and equipment	0	43	0
Net cash used in investing activities	-344	-132	-294
Financing activities
Net proceeds from issuance of common stock upon initial public offering	57,807	0	0
Proceeds from exercise of preferred stock warrants	8,150	0	0
Proceeds from exercise of stock options	23	6	11
Proceeds from sale of convertible preferred stock, net of cash paid for issuance costs	0	29,668	10,615
Proceeds from sale of convertible preferred stock warrants	0	2,381	0
Net cash provided by financing activities	65,980	32,055	10,626
Net increase in cash and cash equivalents	44,967	17,625	754
Cash and cash equivalents, beginning of period	30,387	12,762	12,008
Cash and cash equivalents, end of period	75,354	30,387	12,762
Conversion of shares of preferred stock into shares of common stock [Member]
Supplemental disclosures:
Conversion into shares of common stock	81,394	0	0
Conversion of preferred stock warrants into shares of common stock [Member]
Supplemental disclosures:
Conversion into shares of common stock	$7,613	$0	$0

Description_of_the_Business

Description of the Business	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business	Description of the Business
	Immune Design Corp. (we, us or our) is a clinical-stage immunotherapy company with next-generation in vivo approaches designed to enable the body’s immune system to fight disease. We have engineered our technologies to activate the immune system’s natural ability to create tumor-specific cytotoxic T cells (CTLs) to fight cancer. We are developing multiple product candidates from our two discovery platforms, IMDZVex™ ("ZVex™") and GLAAS™. Our product candidates, LV305, CMB305 and G100, utilize multiple immuno-oncology approaches and are in Phase 1 clinical trials and we expect to initiate a Phase 1 clinical trial for CMB305 in the first quarter of 2015. CMB305 combines our two platforms, LV305 and a second agent G305, in a prime-boost approach. G305 is based on our GLAAS platform and is in a Phase 1 clinical trial. Although we plan to focus our development efforts on CMB305 and G100, we plan to conduct a small exploratory trial to compare LV305 and CMB305 in the same tumor types. After reviewing those data, we may elect to separately develop LV305.
	We were incorporated in February 2008 in the State of Delaware. Our operations are headquartered in Seattle, Washington with additional facilities in South San Francisco, California.
	Initial Public Offering
	In July 2014, we completed an initial public offering (the IPO) of 5,000,000 shares of common stock at a price of $12.00 per share. In August 2014, we sold an additional 410,564 shares of common stock directly to our underwriters when they exercised portions of their over-allotment on two separate occasions at $12.00 per share. We received net proceeds of $57.8 million (inclusive of the exercise of the over-allotment) after deducting underwriting discounts and commissions and offering expenses totaling $7.1 million. In connection with the closing of the IPO, all outstanding shares of convertible preferred stock automatically converted into 9,769,422 shares of common stock. In July 2014, prior to the completion of the IPO, warrants to purchase 996,940 shares of common stock were exercised for $8.1 million in cash. Immediately prior to the closing of the IPO, warrants to purchase 978,592 shares were automatically net exercised, resulting in an issuance of an additional 311,923 shares of common stock. The significant number of shares issued in the third quarter of 2014 is expected to impact the year-over-year comparability of our net loss per share calculations through the third quarter of 2015. Upon completion of the IPO, the total shares of common stock authorized was 100,000,000 and the total shares of preferred stock authorized was 10,000,000.
	Reverse Stock Split
	On July 14, 2014, we filed an amendment to our amended and restated certificate of incorporation, effecting a 1-for-8.175 reverse stock split. All issued and outstanding stock and per share amounts contained in our financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	Basis of Presentation and Use of Estimates
	The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP). To conform with GAAP, the preparation of our financial statements requires management to make judgments, assumptions, and estimates that affect the amounts reported in our financial statements and accompanying notes. Estimates are used for, but not limited to, accruals for clinical trial activity, other accrued liabilities, and assumptions used in determining stock-based compensation expenses and convertible preferred stock warrant liability. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable. Actual results could differ materially from those estimates.
	Segments
	We operate in one segment and use cash flow as the primary measure to manage our business and do not segment the business for internal reporting or decision-making purposes.
	Cash and Cash Equivalents
	Cash equivalents are highly liquid investments with a maturity of 90 days or less at the date of purchase and consist of investments in money market funds. In addition, we maintain cash balances with financial institutions in excess of insured limits and do not anticipate any losses on such cash balances.
	Concentration of Risk
	We limit our credit risk associated with cash and cash equivalents by placing our deposits with banks we believe are highly creditworthy and our investments with highly rated money market funds.
	Accounts Receivable
	Accounts receivable are amounts due from other companies related primarily to licensing fees, product sales and research and development services. We considered the need for an allowance for doubtful accounts and have concluded that no allowance was needed as of December 31, 2014 or 2013, as the estimated risk of loss on our accounts receivable was determined to be minimal.
	Inventory
	Inventory is recorded at the lower of cost or market. Cost includes amounts related to materials and labor, and is determined on a specific identification basis in a manner which approximates the first-in, first-out method. We record adjustments to inventory for potentially excess, obsolete, expired, or impaired items. We recorded $0 and $126,000 in cost of product sales associated with the expiration and obsolescence of products in 2014 and 2013, respectively.
	Property and Equipment
	Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed using the straight-line method over an estimated useful life that is generally three years, while leasehold improvements are amortized over the shorter of their estimated useful lives or the related lease term. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is credited or charged to operations. Maintenance and repairs are expensed as incurred. Asset improvements are capitalized.
	Impairment of Long-Lived Assets
	Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets might not be recoverable. Conditions that would necessitate an impairment assessment include a significant decline in the observable market value of an asset, a significant change in the extent or manner in which an asset is used, or any other significant adverse change that would indicate that the carrying amount of an asset is not recoverable.
	Accrued Liabilities
	Accrued liabilities represent accrued compensation including vacation accruals, unearned revenue and accrued expenses. As part of the process of preparing our financial statements, we are required to estimate our accrued professional services and research and development expenses. This process involves reviewing contracts and vendor agreements, communicating with our applicable personnel to identify services that have been performed on our behalf. We estimate the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual cost. We make estimates of our accrued expenses as of each balance sheet date in our financial statements based on facts and circumstances known to us.
	We base our expenses related to contract manufacturing and clinical trials on our estimates of the services received and efforts expended pursuant to contracts with multiple contract manufacturing organizations and clinical research organizations that conduct and manage supply and clinical trials on our behalf. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, we may report amounts that are too high or too low in any particular period. To date, we have not experienced any significant adjustments to our estimates.
	Leases and Deferred Rent
	We have entered into lease agreements for laboratory and office facilities. These leases are classified as operating leases. Rent expense is recognized on a straight-line basis over the term of the lease. Incentives granted under our facilities leases, including allowances to fund leasehold improvements and rent escalations are accrued as deferred rent. Leasehold improvements funded by the lessor are capitalized and are recognized as reductions to rental expense on a straight-line basis over the term of the lease.
	Series C Convertible Preferred Stock Warrant Liability
	We account for our warrants in accordance with Accounting Standards Codification (ASC) Topic 480-10, Distinguishing Liabilities from Equity, which requires that a financial instrument, other than an outstanding share, that, at inception, includes an obligation to repurchase the issuer’s equity shares regardless of the timing or likelihood of the redemption, shall be classified as a liability. We measure the fair value of the warrant liability based on the fair value of the warrants which we determine based on an allocation of our enterprise value to all classes of equity and preferred stock, including the warrants. In valuing the warrants, we utilized the income method approach in combination with a Monte Carlo simulation, which is a method that evaluates many possible value outcomes to establish the expected value of an asset. This methodology allows the modeling of securities with complex terms, such as the warrants, where path dependency, floors, caps, triggers, changes of control and down round financing provisions can be taken into account. In each reporting period, we record any change in fair value of the warrants as a non-operating gain or loss in the statements of operations. See note 11 for additional information.
	Revenue Recognition
	We derive our revenue from collaboration and licensing agreements and the sale of products associated with material transfer, collaboration and supply agreements.
	Licensing fees, are recognized when the amounts are earned and determinable during the applicable period. We recognize up-front nonrefundable license fees when due under contractual agreements and when we do not have a continuing obligation to provide services related to the agreement. Revenue associated with nonrefundable up-front license fees under arrangements where the license fees and research and development activities cannot be accounted for as separate units of accounting is deferred and recognized as revenue on a straight-line basis over the expected term of our continued involvement in the research and development process. Revenues from the achievement of research and development milestones, if deemed substantive, are recognized as revenue when the milestones are achieved, and the milestone payments are due and collectible. If not deemed substantive, we recognize such milestones as revenue on a straight-line basis over the remaining expected term of continued involvement in the research and development process.
	Milestones are considered substantive if all of the following conditions are met: (1) the milestone is nonrefundable, (2) achievement of the milestone was not reasonably assured at the inception of the arrangement; (3) substantive effort is involved to achieve the milestone; and (4) the amount of the milestone appears reasonable in relation to the effort expended, the other milestones in the arrangement and the related risk associated with the achievement of the milestone and any ongoing research and development or other services are priced at fair value. Payments received in advance of work performed are recorded as unearned revenue.
	Certain agreements from which we derive our revenue include multiple deliverables. We recognize the revenue for each deliverable at fair value determined to be estimated selling price in cases when neither vendor specific objective evidence nor third-party evidence is available.
	Revenue is recognized when all of the following criteria are met: (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 evaluation of these revenue recognition criteria requires significant management judgment. For instance, we use judgment to assess collectability based on factors such as the customer’s creditworthiness and past collection history, if applicable. If we determine that collection of a payment is not reasonably assured, revenue recognition is deferred until receipt of payment. We also use judgment to assess whether a price is fixed or determinable including but not limited to, reviewing contractual terms and conditions related to payment terms.
	Revenue from product sales of GLA is recognized when the risk of loss has passed to the customer or deferred until such time that risk of loss has passed. All revenues associated from the sale of GLA products supplied by us are reported under product sales with the applicable costs reported under cost of product sales. Product sales consist of the direct costs associated with the manufacture and formulation of GLA, including costs to purchase raw materials, third-party contract manufacturing costs, assay testing and ongoing product stability testing.
	We consider significant revenue concentrations to be customers who account for 10% or more of total revenues generated by us during the periods presented. We had collaboration partners that accounted for 55%, 28% and 16% of revenue for the year ended December 31, 2014, 77% and 13% of revenue for the year ended December 31, 2013; 50%, 34% and 12% of revenue for the year ended December 31, 2012. The collaboration partners owed a total of 100% of accounts receivable as of December 31, 2014 and 2013, respectively. We do not believe the loss of such customers would have a material adverse effect on us.
	Stock-Based Compensation
	We account for stock-based compensation under the fair value method. Stock-based compensation costs related to employees and directors is measured at the grant date, based on the fair-value-based measurement of the award estimated using the Black-Scholes option-pricing model, and is recognized as expense over the requisite service period on a straight-line basis.
	Options granted to non-employee service providers are accounted for at estimated fair value using the Black-Scholes option-pricing model and are remeasured over the vesting term as earned.
	We recognize compensation expense for only the portion of options expected to vest. Therefore, management applied an estimated forfeiture rate that was derived from historical employee termination behavior. If the actual number of forfeitures differs from these estimates, adjustments to compensation expense may be required in future periods.
	Research and Development
	Research and development costs are expensed as incurred. Research and development costs primarily include personnel costs, materials and manufacturing to support clinical trials, fees paid to consultants and outside service providers, costs to conduct clinical trials and allocated overhead. Amounts incurred in connection with collaboration agreements are also included in research and development expense. Payments made prior to the receipt of goods or services to be used in research and development are deferred until the goods or services are received.
	Income Taxes
	Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and the operating loss and tax credit carry forwards. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets and liabilities are measured at the balance sheet date using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period such tax rate changes are enacted. Our net deferred tax asset has been fully offset by a valuation allowance because of our history of losses. Any potential accrued interest and penalties related to unrecognized tax benefits within operations would be recorded as income tax expense. To date, there have been no interest or penalties charged to us related to the underpayment of income taxes.
	Comprehensive Loss
	Comprehensive loss is comprised of net loss and certain changes in equity that are excluded from net loss. There was no difference between comprehensive loss and net loss for the years ended December 31, 2014, 2013 and 2012.
	Subsequent Events
	We consider events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure.
	Recent Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-15, related to an entity’s ability to continue as a going concern. ASU 2014-15 requires an entity's management to evaluate whether there are conditions or events that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued. Public entities are required to apply ASU 2014-15 for annual reporting periods ending after December 15, 2016, and interim periods thereafter. Early application is permitted. We are evaluating the guidance to determine the potential impact on our results of operations, financial condition, cash flows, and financial statement disclosures.
	In May 2014, the FASB, issued ASU No. 2014-09, related to the recognition of revenue. ASU 2014-09 requires entities to recognize revenue through the application of a five step model, which includes identification of the contract, identification of the performance obligations, determination of the transaction price, allocation of the transaction price to the performance obligations, and recognition of revenue as the entity satisfies the performance obligations. ASU 2014-09 is effective retrospectively for annual or interim reporting periods beginning after December 15, 2016, with early application not permitted. We are evaluating the guidance to determine the potential impact on our results of operations, financial condition, cash flows, and financial statement disclosures.

Net_Loss_Per_Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share
	We compute net loss per share attributable to common stockholders using the two-class method required for participating securities. We consider all series of our convertible preferred stock to be participating securities. In accordance with the two-class method, earnings allocated to these participating securities, which include participation rights in undistributed earnings, are subtracted from net income to determine total undistributed earnings to be allocated to common stockholders.
	Basic net loss per share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Because of net losses recognized in each period, potential common shares issuable upon the exercise of outstanding stock options and warrants and the conversion of preferred shares in the IPO into common shares have not been reflected in the calculation of diluted net loss per share due to the anti-dilutive effect. Diluted net loss per share, therefore, does not differ from basic net loss per share.
	The common stock issuable upon the conversion or exercise of the following dilutive securities has been excluded from the diluted net loss per share attributable to common stockholders calculation because their effect would have been antidilutive for the periods presented:
		DECEMBER 31,
		2014	2013	2012
	Convertible preferred stock	—	9,769,422	5,818,356
	Options to purchase common stock	1,907,091	1,463,747	634,455
	Warrants to purchase convertible preferred stock	—	1,975,532	—
		1,907,091	13,208,701	6,452,811

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	We measure and record cash and cash equivalents and convertible preferred stock warrant liabilities at fair value in the accompanying financial statements. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, or an exit price, in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value, is as follows:
	Level 1: Quoted prices in active markets for identical assets or liabilities.
	Level 2: Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	Level 1 securities consist of highly liquid money market funds. The fair value of Level 1 assets has been determined using quoted prices in active markets for identical assets.
	In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3 within the valuation hierarchy. The Level 3 preferred stock warrant liability is measured at its estimated fair value on a recurring basis using the income method approach in combination with a Monte Carlo simulation. Inputs used to determine estimated fair value include the estimated fair value of the underlying stock at the valuation measurement date, the multiple scenarios outlining probabilities and the remaining contractual term of the warrants, risk-free interest rates, expected dividends, and the expected volatility of the price of the underlying stock.
	The following table summarizes our financial assets and liabilities measured at fair value on a recurring basis (in thousands):
			DECEMBER 31, 2014
			LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
	Assets:
	Money market funds		$	73,098	$	—	$	—	$	73,098
			DECEMBER 31, 2013
			LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
	Assets:
	Money market funds		$	30,030	$	—	$	—	$	30,030
	Liabilities:
	Convertible preferred stock warrant liability		$	—	$	—	$	3,336	$	3,336
	We classify the convertible preferred stock warrant liability within Level 3 because the warrant liability is valued using valuation models with significant unobservable inputs. The estimated fair value of warrants accounted for as liabilities was determined on the issuance date and are subsequently remeasured to fair value at each reporting date. The change in fair value of the warrants is recorded in the statements of operations as a non-operating gain or loss by using a Monte Carlo option pricing model with the following assumptions:
	Upon the issuance in October 2013 of our Series C convertible preferred stock, we used the following assumptions to estimate fair value: equity value of the entity, different conversion prices for different scenarios, time to maturity of 1.7 to 2.0 years under the different exercise scenarios, volatility of 82% and risk free interest rate of 0.3%.
	For December 31, 2013, we used the following assumptions to estimate fair value: equity value of the entity, different conversion prices for different scenarios, time to maturity of 1.2 to 1.7 years under the different exercise scenarios, volatility of 82% and risk free interest rate of 0.3%.
	In July 2014, immediately prior to the closing of the IPO all of our convertible preferred stock warrants were exercised. As of the exercise date, we used our IPO price to estimate the fair value of the warrants. Upon exercise of the warrants, the convertible preferred stock warrant liability was reclassified to stockholders' equity (deficit). See note 8 for additional discussion of the warrant exercise.
	The following table shows the reconciliation of the convertible preferred stock warrant liability measured and recorded at fair value on a recurring basis, using significant unobservable inputs (Level 3) (in thousands):
		ESTIMATED
		FAIR VALUE
	Balance as of January 1, 2013	$	—
	Fair value at issuance of convertible preferred stock warrant liability (October 16, 2013)	2,381
	Change in fair value of convertible preferred stock warrant liability	955
	Balance as of December 31, 2013	3,336
	Change in fair value of convertible preferred stock warrant liability	4,277
	Conversion of preferred stock warrant liability into additional-paid-in-capital	(7,613		)
	Balance as of December 31, 2014	$	—

Inventory

Inventory	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventory	Inventory
	Inventory consists of the following (in thousands):
		DECEMBER 31,
		2014		2013
	Raw materials	$	—	$	13
	Finished goods	25		4
	Total inventory	$	25	$	17

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment
	Property and equipment consists of the following (in thousands):
		DECEMBER 31,
		2014			2013
	Laboratory equipment	$	2,060		$	1,934
	Leasehold improvements	135			98
	Computer equipment and software	285			188
	Office equipment, furniture, and fixtures	124			47
	Total	2,604			2,267
	Less: accumulated depreciation and amortization	(2,203		)	(1,972		)
	Total property and equipment, net	$	401		$	295
	Depreciation and amortization expense was $238,000, $407,000 and $548,000 for the years ended December 31, 2014, 2013 and 2012, respectively.

Accrued_Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities
	Accrued liabilities consist of the following (in thousands):
		DECEMBER 31,
		2014		2013
	Research and development services	$	1,845	$	214
	Legal and professional services	1,253		191
	Employee compensation	1,379		649
	Unearned revenue	524		28
	Total accrued liabilities	$	5,001	$	1,082

Series_C_Convertible_Preferred

Series C Convertible Preferred Stock Warrant Liability	12 Months Ended
	Dec. 31, 2014
Other Liabilities Disclosure [Abstract]
Series C Convertible Preferred Stock Warrant Liability	Series C Convertible Preferred Stock Warrant Liability
	In October 2013, in connection with the issuance of our Series C convertible preferred stock, we issued fully exercisable warrants for the purchase of 1,975,532 shares of our Series C convertible preferred stock at an exercise price of $8.175 per share.
	All warrants were unexercised as of December 31, 2013. The estimated fair value for the 2013 warrants as of December 31, 2013 was $3.3 million. The fair value of the 2013 warrants was determined using the income method valuation model in combination with a Monte Carlo simulation in consideration of multiple early exercise triggers associated with the 2013 warrants.
	In April 2014, we amended the warrants to provide for their automatic net exercise if the IPO price exceeded the exercise price, immediately prior to the closing of the IPO. In July 2014, immediately prior to the closing of the IPO, warrants representing 996,940 shares of common stock were exercised for $8.1 million in cash and warrants representing 978,592 shares of common stock were automatically net exercised for a total of 311,923 shares of common stock. Upon exercise of the warrants, the convertible preferred stock warrant liability was reclassified to stockholders' equity (deficit).
	Convertible Preferred Stock
	In October 2013, we issued and sold 3,951,066 shares of our Series C convertible preferred stock at a price of $8.18 per share resulting in gross proceeds of $32.3 million, pursuant to a Series C convertible preferred stock and warrant purchase agreement. In connection with the issuance and sale of Series C convertible preferred stock we issued to the purchasers warrants, or 2013 warrants, to purchase an aggregate of 1,975,532 shares of our Series C convertible preferred stock at an exercise price of $8.175 per share.
	In November 2012, we received gross proceeds of $10.6 million in exchange for the issuance of 1,130,165 shares of Series B convertible preferred stock at a price per share of $9.41. In aggregate, we received gross proceeds of $34.0 million in exchange for the issuance of 3,616,529 shares of Series B convertible preferred stock at a price per share of $9.41 between October 2010 and November 2012.
	In aggregate, we received gross proceeds of $18.0 million in exchange for the issuance of 2,201,827 shares of Series A convertible preferred stock at a price per preferred share of $8.18 between June 2008 and January 2010.
	A summary of convertible preferred stock is as follows (amounts in thousands, except share and per share data):
		DECEMBER 31, 2013
		ISSUED PRICE		SHARES	SHARES	AGGREGATE		CARRYING
		PER SHARE		AUTHORIZED	ISSUED AND	LIQUIDATION		VALUE
					OUTSTANDING	PREFERENCE
	Series A	$	8.18	2,201,834	2,201,827	$	18,000	$	17,922
	Series B	$	9.41	3,616,539	3,616,529	34,000		33,804
	Series C	$	8.18	7,064,220	3,951,066	32,300		29,668
				12,882,593	9,769,422	$	84,300	$	81,394
	Each holder of convertible preferred stock is entitled to the number of votes equal to the number of our shares of common stock into which such shares of convertible preferred stock are convertible. Each share of convertible preferred stock is convertible at the option of the holder into the number of fully paid and non-assessable shares of common stock that result from dividing the original issue price by the conversion price of the convertible preferred stock. Currently, the conversion ratio for each series of convertible preferred stock is 1:1.
	Holders of convertible preferred stock are entitled to receive noncumulative dividends at the rate of 8.0% per annum for each share of convertible preferred stock outstanding, when, and if declared by the board of directors. These dividends are payable in preference to common stock dividends. To date, we have not declared or paid any dividends. Convertible preferred stockholders are also entitled to receive dividends in a per share amount equal, on an as-if-converted basis, to the amount paid or set aside for each share of common stock.
	In the event of our liquidation, dissolution, or winding up, the holders of convertible preferred stock will be entitled to receive payment out of the assets legally available for distribution for each share of convertible preferred stock held by them, of an amount per share of convertible preferred stock equal to the original issue price plus all declared and unpaid dividends on the convertible preferred stock. In the event that the available funds and assets are insufficient for full payment to the holders of convertible preferred stock on a per-share basis as outlined above, the entire assets and funds legally available for distribution will be distributed ratably among convertible preferred stock in proportion to the full amount to which they would otherwise be respectively entitled. Before any distribution or payment will be made to the holders of any common stock, payment shall be made first to the holders of Series C preferred stock, second to holders of Series B preferred stock, and third to the holders of Series A preferred stock. Upon completion of the distribution of assets as set forth above, all of the remaining assets, if any, will be distributed ratably among the holders of convertible preferred stock, on an as-if converted basis, and common stock.
	In connection with the completion of the Company's IPO in July 2014, all outstanding shares of convertible preferred stock converted into 9,769,422 shares of common stock and all related warrants were exercised. See Note 8 for additional discussion of the exercise of the warrants.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Operating Leases
	We entered into a non-cancelable operating sublease agreement in September 2008, for office and research facilities at another Seattle, Washington location, and amended the lease in July 2009, September 2009, March 2010, and April 2010. In August 2012, we entered into a lease directly with the landlord of the building under the same material terms as our sublease, which sublease was then terminated. The lease provided for a leasehold improvement allowance of $448,000, which was reflected on the balance sheet as of December 31, 2012 as a leasehold improvement in property and equipment and as deferred rent. The lease also required us to pay additional amounts for operating and maintenance expenses. In March 2013, the lease for this facility expired and the associated leasehold improvements and accumulated depreciation were disposed as of March 31, 2013.
	In December 2012, we entered into an operating sublease agreement for lab and office space at our new location in Seattle, Washington. The lease commenced in February 2013 and continues through November 2016, with an option to extend the term for an additional month. The terms of the facility lease provide for rental payments on a monthly basis and on a graduated scale. We recognize rent expense on a straight-line basis over the lease period and accrue for rent expense incurred but not paid. The lease also requires us to pay additional amounts for operating and maintenance expenses. As of December 31, 2014 and 2013, we have incurred $37,000 and $98,000, respectively, in leasehold improvements related to the lease and have recorded accumulated amortization of $50,000 and $22,000, as of December 31, 2014 and 2013, respectively.
	In December 2013, we entered into a new operating lease agreement for office space in South San Francisco, California, and amended the lease in October and November 2014. The amended lease commenced in January 2015 and continues through January 2020, with an option to extend for an additional five years. The terms of the office lease provide for rental payments on a monthly basis and on a graduated scale. We recognize rent expense on a straight-line basis over the lease period and accrue for rent expense incurred but not paid. The lease also requires us to pay additional amounts for operating and maintenance expenses beginning January 2016. With the execution of the amended lease, we were required to provide a $121,000 letter of credit as a security deposit. As of December 31, 2014, no funds had been drawn down on the letter of credit.
	As of December 31, 2014, future minimum lease payments are as follows (in thousands):
	2015	$	718
	2016	713
	2017	361
	2018	372
	2019	383
	Total future minimum lease payments	$	2,547
	Rent expense under operating leases was approximately $576,000, $561,000 and $325,000, for the years ended December 31, 2014, 2013 and 2012, respectively.
	Contingencies
	We are also contingently obligated to pay any potential future milestone payments to third parties as part of certain collaboration and licensing agreements, which could total up to $2.4 million in aggregate payments for the first licensed GLA product we develop, up to $1.3 million in aggregate payments for each subsequent licensed GLA product we develop and up to $1.9 million in aggregate payments for the ZVex products we develop. It also does not include any potential future royalty payments we may be required to make under our licensing agreements as described in Note 10.
	Payments under these agreements are uncertain due to the occurrence of the events requiring payment under these agreements, including our share of potential future milestone and royalty payments. These payments generally become due and payable only upon achievement of certain clinical development, regulatory or commercial milestones.

License_and_Collaboration_Agre

License and Collaboration Agreements	12 Months Ended
	Dec. 31, 2014
Research and Development [Abstract]
License and Collaboration Agreements	License and Collaboration Agreements
	Licenses Granted
	In August 2014, we entered into an agreement with Sanofi under which we granted Sanofi an exclusive license for use of our GLAAS platform to discover, develop and commercialize products to treat a selected food allergy. Upon execution of the agreement, we received a $3.5 million upfront payment, recognized as revenue during the year ended December 31, 2014. The agreement provides for additional payments of up to $168.0 million based upon the attainment of certain development and commercialization milestones, and tiered royalties on sales of approved products. Sanofi may terminate the agreement at any time upon six months' written notice.
	In October 2010, we entered into three separate license agreements with MedImmune, LLC (MedImmune) pursuant to which we granted MedImmune a worldwide, sublicensable, exclusive license to use GLA to develop and sell vaccines in three different infectious disease indications. In 2010, MedImmune paid us upfront payments under the license agreements. Under each license agreement, MedImmune is obligated to make additional payments based on achievement of certain development, regulatory, and commercial milestones for the licensed indication. MedImmune is also obligated to pay us a low double-digit percentage share of non-royalty payments that it receives from sublicensees and a mid single-digit royalty payments on net sales of licensed products, which royalty is subject to reduction under certain circumstances. Through December 31, 2014, MedImmune has paid us an aggregate of $5.5 million in upfront payments under the license agreements. Under each license agreement, MedImmune is obligated to make additional aggregate payments of $62.9 million to $75.0 million, depending on the infectious disease indication and the achievement of certain development, regulatory and commercial milestones for the licensed indication. For the year ended December 31, 2014 we recognized $1.0 million in revenue for the achievement of development milestones under these license agreements.
	In May 2013, we entered into a nonexclusive license agreement granting Medicago, Inc. (Medicago) a right to research, develop, and commercialize GLA in the field of pandemic influenza. Medicago paid an upfront payment of $500,000 under the license agreement, which was recognized as revenue during the year ended December 31, 2013, and is also obligated to make additional payments of up to $9.5 million based on achievement of certain development and government contract milestones for the licensed indication. Medicago is also obligated to pay us a mid single-digit royalty on net sales of licensed products, which royalty is subject to reduction under license expiration.
	In October 2011, we entered into an amended material transfer agreement with Sanofi US Services, Inc. which included an exclusive option to license GLA in the field of allergy and contract research support in exchange for multiple scheduled payments. We allocated a portion of the total payments as license income and the remaining portion to contract research services. We recognized $805,000 in license revenue and $200,000 in other revenue associated with this agreement in 2012.
	Licenses Acquired
	In July 2008, we licensed certain rights to research, develop, and commercialize GLA from the Infectious Disease Research Institute (IDRI) and amended the agreement in 2010. We paid an upfront fee and issued shares of our common stock valued at $59,000 for the license. We recorded the upfront cash payment and the fair value of the common stock as research and development expense in 2008, as the licensed rights had no alternative future use.
	In addition, we agreed to pay certain fees in the future if we should elect to continue development of the applicable technologies, including payments upon achievement of certain development and commercialization milestones and royalty payments of single-digit percentage of net sales, if and when commercialized; however, we may terminate our development program at any time without obligation to IDRI. Under our license agreement with IDRI, we are obligated to share with IDRI a percentage of payments received from third-party licensees.
	Through December 31, 2014, we have paid IDRI an aggregate of $1.9 million in upfront fees, milestone payments and sublicense revenue related to our sublicensees. We expensed these amounts to research and development expense, as the rights had no alternative future use. In 2013 we paid $140,000 in license related milestone payments which were expensed in research and development expenses. We are obligated to pay IDRI up to $2.4 million in additional payments based on the achievement of certain developmental and regulatory milestones for the first GLA product, and up to $1.3 million in additional payments based on the achievement of certain developmental and regulatory milestones for each subsequent GLA product.
	In 2009, we licensed certain patent rights directed to the production of dendritic cell-targeted therapeutic and prophylactic immunization strategies from the California Institute of Technology (Caltech) in exchange for shares of our common stock valued at $25,000. We make annual minimum royalty payments under the license. In addition, we agreed to pay certain fees in the future, including milestone payments upon achievement of certain development and commercialization milestones and royalty payments on net sales in the low single-digit percentage, if and when commercialized, if we should elect to continue development of the related technology; however, we may terminate our development program at any time without further obligation to Caltech. In addition, we are required to pay Caltech up to an aggregate of $1.6 million in additional payments upon the achievement of certain regulatory and sales milestones.
	Collaborations
	In October 2014, we entered into a collaboration with Sanofi Pasteur for the development of a Herpes Simplex Virus immune therapy. Sanofi Pasteur and Immune Design will each contribute product candidates to the collaboration: Sanofi Pasteur will contribute HSV-529, a clinical-stage replication-defective HSV vaccine product candidate, and Immune Design will contribute G103, our preclinical trivalent vaccine product candidate. The collaboration will explore the potential of various combinations of agents, including leveraging Immune Design's GLAAS platform, with the goal to select the best potential immune therapy for patients. Each company will develop the products jointly through Phase 2 clinical trials, at which point Sanofi Pasteur intends to continue development of the most promising candidate and be responsible for commercialization. Sanofi Pasteur will bear the costs of all preclinical and clinical development, with Immune Design providing a specific formulation of GLA from the GLAAS platform at its cost through Phase 2 studies. Immune Design will be eligible to receive future milestone and royalty payments on any product developed from the collaboration. The Company recognizes funding from collaborative research and development efforts as revenue as the Company performs or delivers the related services in accordance with contract terms as long as the Company will receive payment for such services upon standard payment terms. The costs of the related services performed are recorded as research and development expenses on the statement of operations. For the year ended December 31, 2014, the Company recognized $1.1 million in revenue under this collaboration arrangement. As of December 31, 2014, the Company has an outstanding receivable of $1.5 million under this collaboration agreement of which $492,000 was unearned.

Convertible_Preferred_Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Convertible Preferred Stock	Series C Convertible Preferred Stock Warrant Liability
	In October 2013, in connection with the issuance of our Series C convertible preferred stock, we issued fully exercisable warrants for the purchase of 1,975,532 shares of our Series C convertible preferred stock at an exercise price of $8.175 per share.
	All warrants were unexercised as of December 31, 2013. The estimated fair value for the 2013 warrants as of December 31, 2013 was $3.3 million. The fair value of the 2013 warrants was determined using the income method valuation model in combination with a Monte Carlo simulation in consideration of multiple early exercise triggers associated with the 2013 warrants.
	In April 2014, we amended the warrants to provide for their automatic net exercise if the IPO price exceeded the exercise price, immediately prior to the closing of the IPO. In July 2014, immediately prior to the closing of the IPO, warrants representing 996,940 shares of common stock were exercised for $8.1 million in cash and warrants representing 978,592 shares of common stock were automatically net exercised for a total of 311,923 shares of common stock. Upon exercise of the warrants, the convertible preferred stock warrant liability was reclassified to stockholders' equity (deficit).
	Convertible Preferred Stock
	In October 2013, we issued and sold 3,951,066 shares of our Series C convertible preferred stock at a price of $8.18 per share resulting in gross proceeds of $32.3 million, pursuant to a Series C convertible preferred stock and warrant purchase agreement. In connection with the issuance and sale of Series C convertible preferred stock we issued to the purchasers warrants, or 2013 warrants, to purchase an aggregate of 1,975,532 shares of our Series C convertible preferred stock at an exercise price of $8.175 per share.
	In November 2012, we received gross proceeds of $10.6 million in exchange for the issuance of 1,130,165 shares of Series B convertible preferred stock at a price per share of $9.41. In aggregate, we received gross proceeds of $34.0 million in exchange for the issuance of 3,616,529 shares of Series B convertible preferred stock at a price per share of $9.41 between October 2010 and November 2012.
	In aggregate, we received gross proceeds of $18.0 million in exchange for the issuance of 2,201,827 shares of Series A convertible preferred stock at a price per preferred share of $8.18 between June 2008 and January 2010.
	A summary of convertible preferred stock is as follows (amounts in thousands, except share and per share data):
		DECEMBER 31, 2013
		ISSUED PRICE		SHARES	SHARES	AGGREGATE		CARRYING
		PER SHARE		AUTHORIZED	ISSUED AND	LIQUIDATION		VALUE
					OUTSTANDING	PREFERENCE
	Series A	$	8.18	2,201,834	2,201,827	$	18,000	$	17,922
	Series B	$	9.41	3,616,539	3,616,529	34,000		33,804
	Series C	$	8.18	7,064,220	3,951,066	32,300		29,668
				12,882,593	9,769,422	$	84,300	$	81,394
	Each holder of convertible preferred stock is entitled to the number of votes equal to the number of our shares of common stock into which such shares of convertible preferred stock are convertible. Each share of convertible preferred stock is convertible at the option of the holder into the number of fully paid and non-assessable shares of common stock that result from dividing the original issue price by the conversion price of the convertible preferred stock. Currently, the conversion ratio for each series of convertible preferred stock is 1:1.
	Holders of convertible preferred stock are entitled to receive noncumulative dividends at the rate of 8.0% per annum for each share of convertible preferred stock outstanding, when, and if declared by the board of directors. These dividends are payable in preference to common stock dividends. To date, we have not declared or paid any dividends. Convertible preferred stockholders are also entitled to receive dividends in a per share amount equal, on an as-if-converted basis, to the amount paid or set aside for each share of common stock.
	In the event of our liquidation, dissolution, or winding up, the holders of convertible preferred stock will be entitled to receive payment out of the assets legally available for distribution for each share of convertible preferred stock held by them, of an amount per share of convertible preferred stock equal to the original issue price plus all declared and unpaid dividends on the convertible preferred stock. In the event that the available funds and assets are insufficient for full payment to the holders of convertible preferred stock on a per-share basis as outlined above, the entire assets and funds legally available for distribution will be distributed ratably among convertible preferred stock in proportion to the full amount to which they would otherwise be respectively entitled. Before any distribution or payment will be made to the holders of any common stock, payment shall be made first to the holders of Series C preferred stock, second to holders of Series B preferred stock, and third to the holders of Series A preferred stock. Upon completion of the distribution of assets as set forth above, all of the remaining assets, if any, will be distributed ratably among the holders of convertible preferred stock, on an as-if converted basis, and common stock.
	In connection with the completion of the Company's IPO in July 2014, all outstanding shares of convertible preferred stock converted into 9,769,422 shares of common stock and all related warrants were exercised. See Note 8 for additional discussion of the exercise of the warrants.

Stockholders_Equity_Deficit

Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Stockholders' Equity (Deficit)	Stockholders’ Equity (Deficit)
	Common Stock
	We had 16,878,817 and 369,460 shares of common stock outstanding as of December 31, 2014 and 2013, respectively. Shares of common stock reserved for future issuance were as follows:
			AS OF DECEMBER 31,
			2014			2013
	Shares to be issued upon conversion of convertible preferred stock		—			9,769,422
	Shares to be issued upon exercise of convertible preferred stock warrants and conversion of convertible preferred stock		—			1,975,532
	Shares to be issued under the employee stock purchase plan		155,220			—
	Shares to be issued upon exercise of outstanding stock options		1,907,091			1,463,747
	Shares available for future stock option grants		1,274,067			122,829
	Shares of common stock reserved for future issuance		3,336,378			13,331,530
	Equity Incentive Plans
	In April 2014, our board of directors adopted, and in July 2014 our stockholders approved the 2014 Employee Stock Purchase Plan (2014 ESPP). Upon the approval of the 2014 ESPP, 155,220 shares of our common stock were reserved for issuance under. The initial offering period has been set and will begin on April 1, 2015 and end on June 30, 2015. As of December 31, 2014, no shares have been purchased under the plan.
	The total number of shares of common stock available for issuance under the 2014 ESPP will automatically increase annually on January 1 by (i) the lesser of 1% of the total number of shares issued and outstanding as of December 31 of the immediately preceding year or (ii) 200,000 shares. On January 1, 2015, in accordance with the 2014 ESPP annual increase provisions, the authorized shares increased by 168,788 shares.
	In 2008, we adopted the 2008 Equity Incentive Plan (2008 Plan) for eligible employees, officers, directors, and consultants, which provides for the grant of incentive and non-statutory stock options, restricted stock awards, restructured stock unit awards grant, and stock appreciation rights. The terms of the stock awards, including vesting requirements, are determined by the board of directors, subject to the provisions of the 2008 Plan.
	In April 2014, our board of directors adopted, and in July 2014 our stockholders approved, the 2014 Omnibus Incentive Plan (2014 Plan) which provides for the granting of certain awards to eligible employees, officers, directors, and consultants. Upon approval of the 2014 Plan by the stockholders in July 2014, 1,400,000 shares of our common stock were reserved for issuance under the 2014 Plan and we ceased granting stock awards under the 2008 Plan. All shares of common stock subject to awards under the 2008 Plan that expire, terminate, or are otherwise surrendered, canceled, forfeited or repurchased without having been fully exercised or resulting in the issuance of common stock become available for issuance under the 2014 Plan.
	Stock options granted under the 2008 Plan and 2014 Plan generally vest within four years and vested options are exercisable until ten years after the date of grant. Vesting of certain employee options may be accelerated in the event of a change in control of our company. We grant stock options to employees with exercise prices equal to the fair value of our common stock on the date of grant. There were a total of 1,406,767 shares of common stock authorized under the 2014 Plan as of December 31, 2014.
	The total number of shares of common stock available for issuance under the 2014 Plan will automatically increase annually on January 1 by 4% of the total number of shares issued and outstanding as of December 31 of the immediately preceding year. On January 1, 2015, in accordance with the 2014 Plan and annual increase provisions, the authorized shares increased by 675,152 shares.
	Stock Option Activity
	Summary stock option information is as follows:
			OPTIONS			WEIGHTED-		WEIGHTED-	AGGREGATE
			OUTSTANDING			AVERAGE		AVERAGE	INTRINSIC VALUE
						EXERCISE		REMAINING	(IN THOUSANDS)
						PRICE		CONTRACT
								TERM
								(IN YEARS)
	Outstanding at January 1, 2013		634,455			$1.12		8.67
	Granted		872,293			$1.27
	Exercised		(8,499	)		$0.69
	Canceled		(25,141	)		$1.41
	Expired		(9,361	)		$1.26
	Outstanding at December 31, 2013		1,463,747			$1.20		8.67	$	2,552
	Granted		512,643			$12.27
	Exercised		(20,508	)		$1.14
	Canceled		(47,261	)		$3.21
	Expired		(1,530	)		$1.48
	Outstanding at December 31, 2014		1,907,091			$4.16		8.16	$	50,847
	Vested and expected to vest after December 31, 2014		1,781,826			$3.94		8.08	$	47,885
	Exercisable at December 31, 2014		790,576			$1.24		6.87	$	23,352
	As of December 31, 2014, there was $6.1 million of total unrecognized stock-based compensation expense related to nonvested stock options that is expected to be recognized over a weighted-average period of 3.3 years. The total intrinsic value of options exercised during the years ended December 31, 2014, 2013 and 2012 was $243,000, $7,000 and $4,000, respectively.
	Stock-Based Compensation Expense
	Employee stock-based compensation expense recognized was calculated based on awards ultimately expected to vest and has been reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, as necessary, in subsequent periods if actual forfeitures differ from those estimates. Total stock-based compensation expense recognized in our statements of operations is as follows (in thousands):
			YEARS ENDED DECEMBER 31,
			2014				2013			2012
	Employee:
	Research and development		$	421			$	40		$	30
	General and administrative		703				111			75
	Non-Employee:
	Research and development		216				39			43
	General and administrative		4				65			96
	Total stock-based compensation expense		$	1,344			$	255		$	244
	We use the Black-Scholes option pricing model to estimate the fair value of stock options at the grant date. The Black-Scholes option pricing model requires us to make certain estimates and assumptions, including assumptions related to the expected price volatility of our stock, the period during which the options will be outstanding, the rate of return on risk-free investments, and the expected dividend yield of our stock.
	To estimate the fair value of our common stock prior to our IPO, our board of directors periodically determined the per share fair value of our common stock at various dates using valuations performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants Practice Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation. We performed these valuations contemporaneously as of December 31, 2012, October 16, 2013 and March 31, 2014. For financial reporting purposes, we also performed a retrospective valuation on December 31, 2013. Upon the completion of our IPO, the fair value of our common stock has been determined by the trading value of our common stock on NASDAQ.
	The fair values of stock options granted to employees were calculated using the following assumptions:
			YEARS ENDED DECEMBER 31,
			2014		2013		2012
	Weighted-average estimated fair value		$9.32		$2.31		$0.97
	Risk-free interest rate (1)		1.54% - 2.16%		0.97% - 1.99%		0.93% - 1.19%
	Expected term of options (in years) (2)		5.50 - 6.75		5.45 - 6.08		5.85 - 6.07
	Expected stock price volatility (3)		90% - 93%		90%		90%
	Expected dividend yield (4)		—%		—%		—%
	-1	The risk-free interest rate assumption was based on zero-coupon U.S. Treasury instruments that had terms consistent with the expected term of our stock option grants.
	-2	We used the “simplified method” for options to determine the expected term of our stock option grants. Under this approach, the weighted-average expected life is presumed to be the average of the vesting term and the contractual term of the option.
	-3	Volatility is a measure of the amount by which a financial variable, such as share price, has fluctuated or is expected to fluctuate during a period. We analyzed the stock price volatility of companies at a similar stage of development to estimate expected volatility of our stock price.
-4	We have never declared or paid cash dividends and do not presently plan to pay cash dividends in the foreseeable future.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	No provision for income taxes has been recorded for the years ended December 31, 2014, 2013 and 2012 due to the operating losses incurred since inception for which no benefit has been recorded.
	The reconciliation of the U.S. income tax rate to the effective income tax rate for continuing operations is as follows:
		AS OF DECEMBER 31,
		2014			2013
	Statutory tax rate	35	%		35	%
	Effect of:
	State income taxes net of federal tax benefit	—			—
	Permanent differences	(5.09	)		(2.41	)
	Corrections to deferred assets	—			—
	Other	—			0.35
	General business credits	2.02			5.41
	Change in valuation allowance	(31.93	)		(38.35	)
	Effective tax rate	—	%		—	%
	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.
	Significant components of our deferred taxes are as follows (in thousands):
		AS OF DECEMBER 31,
		2014				2013
	Deferred tax assets:
	Net operating loss carryforwards	$	29,052			$	18,898
	Research and development credit	2,658				1,969
	Depreciation and amortization	174				174
	Other temporary differences	292				232
	Gross deferred tax assets	32,176				21,273
	Deferred tax asset valuation allowance	(32,176		)		(21,273		)
	Net deferred tax assets	$	—			$	—
	Realization of deferred tax assets is dependent on future earnings, if any, the timing and amount of which are uncertain. Accordingly, the deferred tax assets have been offset by a valuation allowance. The valuation allowance relates primarily to net deferred tax assets from operating losses and research and development credits. The net deferred tax asset has been fully offset by a valuation allowance. The valuation allowance increased by $10.9 million and $6.1 million during 2014 and 2013, respectively.
	As of December 31, 2014 and December 31, 2013, we had approximately $83.0 million and $54.0 million in federal net operating loss carryforwards and approximately $2.7 million and $2.0 million in federal research and development tax credit carryforwards, respectively. The net operating losses and federal research credits will begin to expire in varying amounts between 2028 and 2034 if not utilized.
	The Tax Reform Act of 1986 (the Act) provides for a limitation on the annual use of net operating loss and research and development tax credit carryforwards following certain ownership changes (as defined by the Act) that could limit our ability to utilize these carryforwards. We may have experienced an ownership change, as defined by the Act, as a result of past financings. Accordingly, our ability to utilize the aforementioned carryforwards may be limited. Additionally, U.S. tax laws limit the time during which these carryforwards may be applied against future taxes; therefore, we may not be able to take full advantage of these carryforwards for federal income tax purposes.
	Certain net operating losses arise from the deductibility for tax purposes of compensation under nonqualified stock options equal to the difference between the fair value of the stock on the date of exercise and the exercise price of the options. For financial reporting purposes, the tax effect of this deduction when recognized is accounted for as a credit to stockholders’ equity. We do not have any excess tax deductions on option exercises.
	We file income tax returns in the U.S. federal jurisdiction as well and plan to file in the state of California. We are not currently under audit in any tax jurisdiction. Tax years from 2008 through 2014 are currently open for audit by federal and state taxing authorities.
	We recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. During the years ended December 31, 2014 and 2013, we did not have any accrued interest or penalties associated with unrecognized benefits. Additionally, we did not have any unrecognized tax benefits at December 31, 2014 or 2013.

Legal_Proceedings

Legal Proceedings	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings	Legal Proceedings
	TheraVectys SA v. Immune Design Corp.
	In October 2013, TheraVectys SA, or TVS, a French biotechnology company, filed a complaint against us in the United States District Court for the District of Delaware. TVS alleged that it had entered into a contractual relationship with Henogen SA, or Henogen, in 2010 with respect to the production of lentiviral vector vaccines for TVS. Henogen is a contract manufacturing organization with which we contracted for the manufacture of our LV305 product candidate. TVS alleged that its contractual relationship with Henogen contained an exclusivity provision limiting Henogen’s ability to participate in the manufacturing process of a vaccine based on lentiviral DNA Flap vectors for third parties, as well as a provision preventing Henogen from sharing or using certain TVS confidential technology for manufacturing processes developed by TVS with or for the benefit of others. TVS alleged that we entered into a contractual relationship with Henogen in 2012 to manufacture lentiviral vectors for vaccines, which TVS contends interfered with its contract with Henogen and resulted in the use of certain TVS confidential information and trade secrets. The complaint asserted three counts for relief: tortious interference with contractual relationship, unfair competition and misappropriation of trade secrets. TVS did not specify its claimed damages, other than to assert that they exceed $75,000. TVS also requested in its complaint injunctive relief enjoining us from importing, receiving possessing or using lentiviral vector vaccines developed or produced by Henogen, but never filed a motion seeking injunctive relief. The parties entered into several stipulations extending the deadline for us to respond to the complaint. On or about April 7, 2014, TVS filed a Notice of Voluntary Dismissal without prejudice of this lawsuit.
	On or about July 24, 2014, shortly after our Registration Statement on Form S-1 was declared effective by the SEC for our initial public offering, TVS filed a new complaint against us in the Chancery Court of the State of Delaware, alleging facts substantially similar to the prior complaint. In addition, the complaint further alleges that we obtained shipments of lentiviral vectors for vaccines from Henogen and are conducting clinical trials with these lentiviral vectors. The complaint asserts four counts for relief: tortious interference with contractual relationship, unfair competition, misappropriation of trade secrets, and unjust enrichment; claimed damages were not specified. The complaint also requested injunctive relief enjoining us from using lentiviral vectors developed or produced by Henogen, using any other materials or information obtained by Henogen, and citing to the FDA or otherwise relying on any clinical trials using lentiviral vector vaccines developed or produced by Henogen.
	On or about July 24, 2014, TVS also filed a motion for expedited proceedings in support of an anticipated motion for preliminary injunction. On August 8, 2014 the court granted TVS’ motion for expedited proceedings and set a hearing date in mid-November 2014 for TVS’ anticipated motion for preliminary injunction. In September 2014, TVS filed a motion to postpone the hearing date and delay the proceedings it previously sought to expedite. The court granted the motion and set a new date for the hearing. On or about December 15, 2014, TVS filed a motion for a preliminary injunction seeking, among other things, to enjoin us from making any use of lentiviral vectors pending final resolution of the litigation. A hearing was held on TVS’s motion in January 2015.
	By order dated March 9, 2015, the Chancery Court denied TVS’ motion for a preliminary injunction. The court has not yet made any final determination on the merits of the lawsuit, which will be determined at a full trial which we expect will occur prior to the end of the third quarter of 2015. We intend to continue to vigorously defend this lawsuit.
	European Patent Oppositions
	In February 2013, a third party filed an opposition at the European Patent Office, or EPO, requesting revocation of European Patent No. 2068918 directed to GLA formulations and uses. This patent is owned by Infectious Disease Research Institute and under license to us. We are vigorously defending the grant of this patent, with a reply to the opposition brief having been filed on September 27, 2013. No date for an oral hearing has yet been set. This patent is an important part of our proprietary position for GLA in Europe. The final outcome of the proceedings is uncertain and will likely not be known for several years.
	In October 2014, TVS filed an opposition at the EPO requesting revocation of European Patent No. 2456786 directed at improvements to our lentiviral vector. This opposition is not substantively related to the ongoing Delaware lawsuit previously disclosed, and to our knowledge, TVS is not using the technology claimed in this patent. We intend to vigorously defend the grant of this patent, and in light of other European patents and patent applications directed to our lentiviral platform technology, we do not believe the validity of this patent will have a material effect on the scope of our patent protection in Europe.

Employee_Benefit_Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plan	Employee Benefit Plan
	We sponsor a 401(k) defined contribution plan for our employees. Employee contributions are voluntary. We may match employee contributions in amounts to be determined at our sole discretion. Currently, we have elected to satisfy the safe-harbor rules by matching contributions equal to 100% of employee salary deferrals that do not exceed 3% of the employee’s compensation, plus 50% matching employee salary deferrals between 3% and 5% of the employee’s compensation. Employer contributions have totaled approximately $153,000, $110,000, and $101,000 for the years ended December 31, 2014, 2013, and 2012 respectively.

Selected_Quarterly_Financial_I

Selected Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Information (Unaudited)	Selected Quarterly Financial Information (Unaudited)
	The following amounts are in thousands, except per share amounts:
		Quarter Ended
		March 31,			June 30,			September 30,			December 31,
		2014			2014			2014			2014
		(unaudited)
	Total revenues	$	25		$	1,064		$	3,544		$	1,800
	Net loss attributable to common stockholders	$	(8,223	)	$	(6,126	)	$	(6,682	)	$	(13,120	)
	Basic and diluted net loss per share attributable to common stockholders	$	(22.25	)	$	(16.57	)	$	(0.55	)	$	(0.78	)
		Quarter Ended
		March 31,			June 30,			September 30,			December 31,
		2013			2013			2013			2013
		(unaudited)
	Total revenues	$	564		$	882		$	129		$	24
	Net loss attributable to common stockholders	$	(2,941	)	$	(3,634	)	$	(3,994	)	$	(5,406	)
	Basic and diluted net loss per share attributable to common stockholders	$	(8.14	)	$	(9.84	)	$	(10.81	)	$	(14.71	)

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events
	By order dated March 9, 2015, the Chancery Court denied TVS’ motion for a preliminary injunction. The court has not yet made any final determination on the merits of the lawsuit, which will be determined at a full trial which we expect will occur prior to the end of the third quarter of 2015. We intend to continue to vigorously defend this lawsuit.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates
	The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP). To conform with GAAP, the preparation of our financial statements requires management to make judgments, assumptions, and estimates that affect the amounts reported in our financial statements and accompanying notes. Estimates are used for, but not limited to, accruals for clinical trial activity, other accrued liabilities, and assumptions used in determining stock-based compensation expenses and convertible preferred stock warrant liability. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable. Actual results could differ materially from those estimates.
Segments	Segments
	We operate in one segment and use cash flow as the primary measure to manage our business and do not segment the business for internal reporting or decision-making purposes.
Cash and Cash Equivalents	Cash and Cash Equivalents
	Cash equivalents are highly liquid investments with a maturity of 90 days or less at the date of purchase and consist of investments in money market funds. In addition, we maintain cash balances with financial institutions in excess of insured limits and do not anticipate any losses on such cash balances.
Concentration of Risk	Concentration of Risk
	We limit our credit risk associated with cash and cash equivalents by placing our deposits with banks we believe are highly creditworthy and our investments with highly rated money market funds.
Accounts Receivable	Accounts Receivable
	Accounts receivable are amounts due from other companies related primarily to licensing fees, product sales and research and development services. We considered the need for an allowance for doubtful accounts and have concluded that no allowance was needed as of December 31, 2014 or 2013, as the estimated risk of loss on our accounts receivable was determined to be minimal.
Inventory	Inventory
	Inventory is recorded at the lower of cost or market. Cost includes amounts related to materials and labor, and is determined on a specific identification basis in a manner which approximates the first-in, first-out method. We record adjustments to inventory for potentially excess, obsolete, expired, or impaired items.
Property and Equipment	Property and Equipment
	Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed using the straight-line method over an estimated useful life that is generally three years, while leasehold improvements are amortized over the shorter of their estimated useful lives or the related lease term. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is credited or charged to operations. Maintenance and repairs are expensed as incurred. Asset improvements are capitalized.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets
	Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets might not be recoverable. Conditions that would necessitate an impairment assessment include a significant decline in the observable market value of an asset, a significant change in the extent or manner in which an asset is used, or any other significant adverse change that would indicate that the carrying amount of an asset is not recoverable.
Accrued Liabilities	Accrued Liabilities
	Accrued liabilities represent accrued compensation including vacation accruals, unearned revenue and accrued expenses. As part of the process of preparing our financial statements, we are required to estimate our accrued professional services and research and development expenses. This process involves reviewing contracts and vendor agreements, communicating with our applicable personnel to identify services that have been performed on our behalf. We estimate the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual cost. We make estimates of our accrued expenses as of each balance sheet date in our financial statements based on facts and circumstances known to us.
	We base our expenses related to contract manufacturing and clinical trials on our estimates of the services received and efforts expended pursuant to contracts with multiple contract manufacturing organizations and clinical research organizations that conduct and manage supply and clinical trials on our behalf. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, we may report amounts that are too high or too low in any particular period. To date, we have not experienced any significant adjustments to our estimates.
Leases and Deferred Rent	Leases and Deferred Rent
	We have entered into lease agreements for laboratory and office facilities. These leases are classified as operating leases. Rent expense is recognized on a straight-line basis over the term of the lease. Incentives granted under our facilities leases, including allowances to fund leasehold improvements and rent escalations are accrued as deferred rent. Leasehold improvements funded by the lessor are capitalized and are recognized as reductions to rental expense on a straight-line basis over the term of the lease.
Series C Convertible Preferred Stock Warrant Liability	Series C Convertible Preferred Stock Warrant Liability
	We account for our warrants in accordance with Accounting Standards Codification (ASC) Topic 480-10, Distinguishing Liabilities from Equity, which requires that a financial instrument, other than an outstanding share, that, at inception, includes an obligation to repurchase the issuer’s equity shares regardless of the timing or likelihood of the redemption, shall be classified as a liability. We measure the fair value of the warrant liability based on the fair value of the warrants which we determine based on an allocation of our enterprise value to all classes of equity and preferred stock, including the warrants. In valuing the warrants, we utilized the income method approach in combination with a Monte Carlo simulation, which is a method that evaluates many possible value outcomes to establish the expected value of an asset. This methodology allows the modeling of securities with complex terms, such as the warrants, where path dependency, floors, caps, triggers, changes of control and down round financing provisions can be taken into account. In each reporting period, we record any change in fair value of the warrants as a non-operating gain or loss in the statements of operations.
Revenue Recognition	Revenue Recognition
	We derive our revenue from collaboration and licensing agreements and the sale of products associated with material transfer, collaboration and supply agreements.
	Licensing fees, are recognized when the amounts are earned and determinable during the applicable period. We recognize up-front nonrefundable license fees when due under contractual agreements and when we do not have a continuing obligation to provide services related to the agreement. Revenue associated with nonrefundable up-front license fees under arrangements where the license fees and research and development activities cannot be accounted for as separate units of accounting is deferred and recognized as revenue on a straight-line basis over the expected term of our continued involvement in the research and development process. Revenues from the achievement of research and development milestones, if deemed substantive, are recognized as revenue when the milestones are achieved, and the milestone payments are due and collectible. If not deemed substantive, we recognize such milestones as revenue on a straight-line basis over the remaining expected term of continued involvement in the research and development process.
	Milestones are considered substantive if all of the following conditions are met: (1) the milestone is nonrefundable, (2) achievement of the milestone was not reasonably assured at the inception of the arrangement; (3) substantive effort is involved to achieve the milestone; and (4) the amount of the milestone appears reasonable in relation to the effort expended, the other milestones in the arrangement and the related risk associated with the achievement of the milestone and any ongoing research and development or other services are priced at fair value. Payments received in advance of work performed are recorded as unearned revenue.
	Certain agreements from which we derive our revenue include multiple deliverables. We recognize the revenue for each deliverable at fair value determined to be estimated selling price in cases when neither vendor specific objective evidence nor third-party evidence is available.
	Revenue is recognized when all of the following criteria are met: (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 evaluation of these revenue recognition criteria requires significant management judgment. For instance, we use judgment to assess collectability based on factors such as the customer’s creditworthiness and past collection history, if applicable. If we determine that collection of a payment is not reasonably assured, revenue recognition is deferred until receipt of payment. We also use judgment to assess whether a price is fixed or determinable including but not limited to, reviewing contractual terms and conditions related to payment terms.
	Revenue from product sales of GLA is recognized when the risk of loss has passed to the customer or deferred until such time that risk of loss has passed. All revenues associated from the sale of GLA products supplied by us are reported under product sales with the applicable costs reported under cost of product sales. Product sales consist of the direct costs associated with the manufacture and formulation of GLA, including costs to purchase raw materials, third-party contract manufacturing costs, assay testing and ongoing product stability testing.
	We consider significant revenue concentrations to be customers who account for 10% or more of total revenues generated by us during the periods presented. We had collaboration partners that accounted for 55%, 28% and 16% of revenue for the year ended December 31, 2014, 77% and 13% of revenue for the year ended December 31, 2013; 50%, 34% and 12% of revenue for the year ended December 31, 2012. The collaboration partners owed a total of 100% of accounts receivable as of December 31, 2014 and 2013, respectively. We do not believe the loss of such customers would have a material adverse effect on us.
Stock-Based Compensation	Stock-Based Compensation
	We account for stock-based compensation under the fair value method. Stock-based compensation costs related to employees and directors is measured at the grant date, based on the fair-value-based measurement of the award estimated using the Black-Scholes option-pricing model, and is recognized as expense over the requisite service period on a straight-line basis.
	Options granted to non-employee service providers are accounted for at estimated fair value using the Black-Scholes option-pricing model and are remeasured over the vesting term as earned.
	We recognize compensation expense for only the portion of options expected to vest. Therefore, management applied an estimated forfeiture rate that was derived from historical employee termination behavior. If the actual number of forfeitures differs from these estimates, adjustments to compensation expense may be required in future periods.
Research and Development	Research and Development
	Research and development costs are expensed as incurred. Research and development costs primarily include personnel costs, materials and manufacturing to support clinical trials, fees paid to consultants and outside service providers, costs to conduct clinical trials and allocated overhead. Amounts incurred in connection with collaboration agreements are also included in research and development expense. Payments made prior to the receipt of goods or services to be used in research and development are deferred until the goods or services are received.
Income Taxes	Income Taxes
	Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and the operating loss and tax credit carry forwards. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets and liabilities are measured at the balance sheet date using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period such tax rate changes are enacted. Our net deferred tax asset has been fully offset by a valuation allowance because of our history of losses. Any potential accrued interest and penalties related to unrecognized tax benefits within operations would be recorded as income tax expense. To date, there have been no interest or penalties charged to us related to the underpayment of income taxes.
Comprehensive Loss	Comprehensive Loss
	Comprehensive loss is comprised of net loss and certain changes in equity that are excluded from net loss. There was no difference between comprehensive loss and net loss for the years ended December 31, 2014, 2013 and 2012.
Subsequent Events	Subsequent Events
	We consider events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-15, related to an entity’s ability to continue as a going concern. ASU 2014-15 requires an entity's management to evaluate whether there are conditions or events that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued. Public entities are required to apply ASU 2014-15 for annual reporting periods ending after December 15, 2016, and interim periods thereafter. Early application is permitted. We are evaluating the guidance to determine the potential impact on our results of operations, financial condition, cash flows, and financial statement disclosures.
	In May 2014, the FASB, issued ASU No. 2014-09, related to the recognition of revenue. ASU 2014-09 requires entities to recognize revenue through the application of a five step model, which includes identification of the contract, identification of the performance obligations, determination of the transaction price, allocation of the transaction price to the performance obligations, and recognition of revenue as the entity satisfies the performance obligations. ASU 2014-09 is effective retrospectively for annual or interim reporting periods beginning after December 15, 2016, with early application not permitted. We are evaluating the guidance to determine the potential impact on our results of operations, financial condition, cash flows, and financial statement disclosures.
Net Loss Per Share	We compute net loss per share attributable to common stockholders using the two-class method required for participating securities. We consider all series of our convertible preferred stock to be participating securities. In accordance with the two-class method, earnings allocated to these participating securities, which include participation rights in undistributed earnings, are subtracted from net income to determine total undistributed earnings to be allocated to common stockholders.
	Basic net loss per share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Because of net losses recognized in each period, potential common shares issuable upon the exercise of outstanding stock options and warrants and the conversion of preferred shares in the IPO into common shares have not been reflected in the calculation of diluted net loss per share due to the anti-dilutive effect. Diluted net loss per share, therefore, does not differ from basic net loss per share.

Net_Loss_Per_Share_Tables

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The common stock issuable upon the conversion or exercise of the following dilutive securities has been excluded from the diluted net loss per share attributable to common stockholders calculation because their effect would have been antidilutive for the periods presented:
		DECEMBER 31,
		2014	2013	2012
	Convertible preferred stock	—	9,769,422	5,818,356
	Options to purchase common stock	1,907,091	1,463,747	634,455
	Warrants to purchase convertible preferred stock	—	1,975,532	—
		1,907,091	13,208,701	6,452,811

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table summarizes our financial assets and liabilities measured at fair value on a recurring basis (in thousands):
			DECEMBER 31, 2014
			LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
	Assets:
	Money market funds		$	73,098	$	—	$	—	$	73,098
			DECEMBER 31, 2013
			LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
	Assets:
	Money market funds		$	30,030	$	—	$	—	$	30,030
	Liabilities:
	Convertible preferred stock warrant liability		$	—	$	—	$	3,336	$	3,336
Reconciliation of Convertible Preferred Stock Warranty Liability Measured and Recorded at Fair Value on a Recurring Basis	The following table shows the reconciliation of the convertible preferred stock warrant liability measured and recorded at fair value on a recurring basis, using significant unobservable inputs (Level 3) (in thousands):
		ESTIMATED
		FAIR VALUE
	Balance as of January 1, 2013	$	—
	Fair value at issuance of convertible preferred stock warrant liability (October 16, 2013)	2,381
	Change in fair value of convertible preferred stock warrant liability	955
	Balance as of December 31, 2013	3,336
	Change in fair value of convertible preferred stock warrant liability	4,277
	Conversion of preferred stock warrant liability into additional-paid-in-capital	(7,613		)
	Balance as of December 31, 2014	$	—

Inventory_Tables

Inventory (Tables)	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventory	Inventory consists of the following (in thousands):
		DECEMBER 31,
		2014		2013
	Raw materials	$	—	$	13
	Finished goods	25		4
	Total inventory	$	25	$	17

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property and equipment consists of the following (in thousands):
		DECEMBER 31,
		2014			2013
	Laboratory equipment	$	2,060		$	1,934
	Leasehold improvements	135			98
	Computer equipment and software	285			188
	Office equipment, furniture, and fixtures	124			47
	Total	2,604			2,267
	Less: accumulated depreciation and amortization	(2,203		)	(1,972		)
	Total property and equipment, net	$	401		$	295

Accrued_Liabilities_Tables

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands):
		DECEMBER 31,
		2014		2013
	Research and development services	$	1,845	$	214
	Legal and professional services	1,253		191
	Employee compensation	1,379		649
	Unearned revenue	524		28
	Total accrued liabilities	$	5,001	$	1,082

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Future minimum lease payments	As of December 31, 2014, future minimum lease payments are as follows (in thousands):
	2015	$	718
	2016	713
	2017	361
	2018	372
	2019	383
	Total future minimum lease payments	$	2,547

Convertible_Preferred_Stock_Ta

Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Schedule of Stock by Class	A summary of convertible preferred stock is as follows (amounts in thousands, except share and per share data):
		DECEMBER 31, 2013
		ISSUED PRICE			SHARES	SHARES	AGGREGATE		CARRYING
		PER SHARE			AUTHORIZED	ISSUED AND	LIQUIDATION		VALUE
						OUTSTANDING	PREFERENCE
	Series A	$	8.18		2,201,834	2,201,827	$	18,000	$	17,922
	Series B	$	9.41		3,616,539	3,616,529	34,000		33,804
	Series C	$	8.18		7,064,220	3,951,066	32,300		29,668
					12,882,593	9,769,422	$	84,300	$	81,394
	hares of common stock reserved for future issuance were as follows:
		AS OF DECEMBER 31,
		2014		2013
	Shares to be issued upon conversion of convertible preferred stock	—		9,769,422
	Shares to be issued upon exercise of convertible preferred stock warrants and conversion of convertible preferred stock	—		1,975,532
	Shares to be issued under the employee stock purchase plan	155,220		—
	Shares to be issued upon exercise of outstanding stock options	1,907,091		1,463,747
	Shares available for future stock option grants	1,274,067		122,829
	Shares of common stock reserved for future issuance	3,336,378		13,331,530

Stockholders_Equity_Deficit_Ta

Stockholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Schedule of Shares of Common Stock Reserved for Future Issuance	A summary of convertible preferred stock is as follows (amounts in thousands, except share and per share data):
			DECEMBER 31, 2013
			ISSUED PRICE				SHARES		SHARES			AGGREGATE		CARRYING
			PER SHARE				AUTHORIZED		ISSUED AND			LIQUIDATION		VALUE
									OUTSTANDING			PREFERENCE
	Series A		$	8.18			2,201,834		2,201,827			$	18,000	$	17,922
	Series B		$	9.41			3,616,539		3,616,529			34,000		33,804
	Series C		$	8.18			7,064,220		3,951,066			32,300		29,668
							12,882,593		9,769,422			$	84,300	$	81,394
	hares of common stock reserved for future issuance were as follows:
			AS OF DECEMBER 31,
			2014			2013
	Shares to be issued upon conversion of convertible preferred stock		—			9,769,422
	Shares to be issued upon exercise of convertible preferred stock warrants and conversion of convertible preferred stock		—			1,975,532
	Shares to be issued under the employee stock purchase plan		155,220			—
	Shares to be issued upon exercise of outstanding stock options		1,907,091			1,463,747
	Shares available for future stock option grants		1,274,067			122,829
	Shares of common stock reserved for future issuance		3,336,378			13,331,530
Summary of Stock Options	Summary stock option information is as follows:
			OPTIONS			WEIGHTED-		WEIGHTED-	AGGREGATE
			OUTSTANDING			AVERAGE		AVERAGE	INTRINSIC VALUE
						EXERCISE		REMAINING	(IN THOUSANDS)
						PRICE		CONTRACT
								TERM
								(IN YEARS)
	Outstanding at January 1, 2013		634,455			$1.12		8.67
	Granted		872,293			$1.27
	Exercised		(8,499	)		$0.69
	Canceled		(25,141	)		$1.41
	Expired		(9,361	)		$1.26
	Outstanding at December 31, 2013		1,463,747			$1.20		8.67	$	2,552
	Granted		512,643			$12.27
	Exercised		(20,508	)		$1.14
	Canceled		(47,261	)		$3.21
	Expired		(1,530	)		$1.48
	Outstanding at December 31, 2014		1,907,091			$4.16		8.16	$	50,847
	Vested and expected to vest after December 31, 2014		1,781,826			$3.94		8.08	$	47,885
	Exercisable at December 31, 2014		790,576			$1.24		6.87	$	23,352
Schedule of Stock-Based Compensation Expense Recognized	Total stock-based compensation expense recognized in our statements of operations is as follows (in thousands):
			YEARS ENDED DECEMBER 31,
			2014				2013			2012
	Employee:
	Research and development		$	421			$	40		$	30
	General and administrative		703				111			75
	Non-Employee:
	Research and development		216				39			43
	General and administrative		4				65			96
	Total stock-based compensation expense		$	1,344			$	255		$	244
Schedule of Fair Value of Stock Options Granted to Employees	The fair values of stock options granted to employees were calculated using the following assumptions:
			YEARS ENDED DECEMBER 31,
			2014		2013		2012
	Weighted-average estimated fair value		$9.32		$2.31		$0.97
	Risk-free interest rate (1)		1.54% - 2.16%		0.97% - 1.99%		0.93% - 1.19%
	Expected term of options (in years) (2)		5.50 - 6.75		5.45 - 6.08		5.85 - 6.07
	Expected stock price volatility (3)		90% - 93%		90%		90%
	Expected dividend yield (4)		—%		—%		—%
	-1	The risk-free interest rate assumption was based on zero-coupon U.S. Treasury instruments that had terms consistent with the expected term of our stock option grants.
	-2	We used the “simplified method” for options to determine the expected term of our stock option grants. Under this approach, the weighted-average expected life is presumed to be the average of the vesting term and the contractual term of the option.
	-3	Volatility is a measure of the amount by which a financial variable, such as share price, has fluctuated or is expected to fluctuate during a period. We analyzed the stock price volatility of companies at a similar stage of development to estimate expected volatility of our stock price.
	-4	We have never declared or paid cash dividends and do not presently plan to pay cash dividends in the foreseeable future.

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation of the U.S. income tax rate to the effective income tax rate for continuing operations is as follows:
		AS OF DECEMBER 31,
		2014			2013
	Statutory tax rate	35	%		35	%
	Effect of:
	State income taxes net of federal tax benefit	—			—
	Permanent differences	(5.09	)		(2.41	)
	Corrections to deferred assets	—			—
	Other	—			0.35
	General business credits	2.02			5.41
	Change in valuation allowance	(31.93	)		(38.35	)
	Effective tax rate	—	%		—	%
Schedule of Deferred Tax Assets and Liabilities	Significant components of our deferred taxes are as follows (in thousands):
		AS OF DECEMBER 31,
		2014				2013
	Deferred tax assets:
	Net operating loss carryforwards	$	29,052			$	18,898
	Research and development credit	2,658				1,969
	Depreciation and amortization	174				174
	Other temporary differences	292				232
	Gross deferred tax assets	32,176				21,273
	Deferred tax asset valuation allowance	(32,176		)		(21,273		)
	Net deferred tax assets	$	—			$	—

Selected_Quarterly_Financial_I1

Selected Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The following amounts are in thousands, except per share amounts:
		Quarter Ended
		March 31,			June 30,			September 30,			December 31,
		2014			2014			2014			2014
		(unaudited)
	Total revenues	$	25		$	1,064		$	3,544		$	1,800
	Net loss attributable to common stockholders	$	(8,223	)	$	(6,126	)	$	(6,682	)	$	(13,120	)
	Basic and diluted net loss per share attributable to common stockholders	$	(22.25	)	$	(16.57	)	$	(0.55	)	$	(0.78	)
		Quarter Ended
		March 31,			June 30,			September 30,			December 31,
		2013			2013			2013			2013
		(unaudited)
	Total revenues	$	564		$	882		$	129		$	24
	Net loss attributable to common stockholders	$	(2,941	)	$	(3,634	)	$	(3,994	)	$	(5,406	)
	Basic and diluted net loss per share attributable to common stockholders	$	(8.14	)	$	(9.84	)	$	(10.81	)	$	(14.71	)

Description_of_the_Business_Na

Description of the Business - Narrative (Details)	12 Months Ended
	Dec. 31, 2014
	platform
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of discovery platforms	2

Description_of_the_Business_In

Description of the Business - Initial Public Offering (Details) (USD $)	0 Months Ended	12 Months Ended			2 Months Ended	1 Months Ended
	Jul. 14, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Aug. 31, 2014	Jul. 31, 2014	Aug. 31, 2014
Class of Stock [Line Items]
Proceeds from warrant exercises		$8,150,000	$0	$0
Shares authorized (in shares)		100,000,000	15,045,871			100,000,000
Reverse stock split ratio	0.1223
Preferred stock, shares authorized		10,000,000	12,882,593			10,000,000
Common stock [Member]
Class of Stock [Line Items]
Proceeds from issuance of initial public offering					57,800,000
IPO [Member] | Common stock [Member]
Class of Stock [Line Items]
Stock issued during period (in shares)						5,000,000
Share price (in USD per share)						$12
Stock issuance costs					7,100,000
Shares converted						9,769,422
Over-Allotment Option [Member] | Common stock [Member]
Class of Stock [Line Items]
Stock issued during period (in shares)							410,564
Share price (in USD per share)					$12		$12
Common stock [Member]
Class of Stock [Line Items]
Stock issued during period (in shares)						311,923
Warrants exercised						978,592
Convertible preferred Stock, Series C [Member]
Class of Stock [Line Items]
Warrants exercised						996,940
Proceeds from warrant exercises						$8,100,000

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Segments (Details)	12 Months Ended
	Dec. 31, 2014
	segment
Accounting Policies [Abstract]
Number of operating segments	1

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Accounts Receivable (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Allowance for doubtful accounts receivable	$0	$0

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Inventory (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Inventory write-down	$0	$126

Summary_of_Significant_Account5

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Estimated useful lives	3 years

Summary_of_Significant_Account6

Summary of Significant Accounting Policies - Revenue Recognition (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Collaboration Partner One [Member] | Sales Revenue, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	55.00%	77.00%	50.00%
Collaboration Partner Two [Member] | Sales Revenue, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	28.00%	13.00%	34.00%
Collaboration Partner Three [Member] | Sales Revenue, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	16.00%		12.00%
Collaboration Partners [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	100.00%	100.00%

Net_Loss_Per_Share_Details

Net Loss Per Share (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,907,091	13,208,701	6,452,811
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	9,769,422	5,818,356
Equity Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,907,091	1,463,747	634,455
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	1,975,532	0

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible preferred stock warrant liability	$0	$3,336
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	73,098	30,030
Convertible preferred stock warrant liability		3,336
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	73,098	30,030
Convertible preferred stock warrant liability		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
Convertible preferred stock warrant liability		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
Convertible preferred stock warrant liability		$3,336

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments - Narrative (Details) (Preferred Stock Warrant Liability [Member])	1 Months Ended	12 Months Ended
	Oct. 31, 2013	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Volatility rate	82.00%	82.00%
Risk free interest rate	0.30%	0.30%
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Time to maturity	1 year 8 months 14 days	1 year 2 months 29 days
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Time to maturity	1 year 11 months 21 days	1 year 8 months 28 days

Fair_Value_of_Financial_Instru4

Fair Value of Financial Instruments - Reconciliation of Convertible Preferred Stock Warranty Liability Measured and Recorded at Fair Value on a Recurring Basis (Details) (Preferred Stock Warrant Liability [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2014
Preferred Stock Warrant Liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$3,336	$0	$0
Fair value at issuance of convertible preferred stock warrant liability (October 16, 2013)		2,381
Change in fair value of convertible preferred stock warrant liability (unaudited)	4,277	955
Conversion of preferred stock warrant liability into additional-paid-in-capital	-7,613
Ending balance		$3,336	$0

Inventory_Details

Inventory (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]
Raw materials	$0	$13
Finished goods	25	4
Total inventory	$25	$17

Property_and_Equipment_Details

Property and Equipment (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$2,604	$2,267
Less: accumulated depreciation and amortization	-2,203	-1,972
Total property and equipment, net	401	295
Depreciation and amortization	238	407	548
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	2,060	1,934
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	135	98
Less: accumulated depreciation and amortization	-50	-22
Total property and equipment, net			448
Computer equipment and software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	285	188
Office equipment, furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$124	$47

Accrued_Liabilities_Details

Accrued Liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]
Research and development services	$1,845	$214
Legal and professional fees	1,253	191
Employee compensation	1,379	649
Unearned revenue	524	28
Total accrued liabilities	$5,001	$1,082

Series_C_Convertible_Preferred1

Series C Convertible Preferred Stock Warrant Liability (Details) (USD $)	12 Months Ended			1 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2014	Oct. 31, 2013
Class of Warrant or Right [Line Items]
Fair value of warrants outstanding	$0	$3,336
Proceeds from warrant exercises	8,150	0	0
Convertible preferred Stock, Series C [Member]
Class of Warrant or Right [Line Items]
Number of warrants exercisable (in shares)					1,975,532
Warrant exercise price (in USD per share)					$8.18
Number of warrants exercised (in shares)				996,940
Proceeds from warrant exercises				$8,100
Common stock [Member]
Class of Warrant or Right [Line Items]
Number of warrants exercised (in shares)				978,592
Stock issued during period (in shares)				311,923

Commitments_and_Contingencies_1

Commitments and Contingencies - Narrative (Details) (USD $)	1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Commitments [Line Items]
Property and equipment, net	$295,000	$401,000	$295,000
Leasehold improvements	98,000	37,000	98,000
Accumulated depreciation, leasehold improvements	1,972,000	2,203,000	1,972,000
Optional lease extension period	5 years
Funds drawn on letter of credit		0
Rent expense		576,000	561,000	325,000
Collaborative Arrangement [Member] | ZVex Product [Member]
Other Commitments [Line Items]
Potential future milestone payments		1,900,000
Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member] | First GLA Product [Member]
Other Commitments [Line Items]
Potential future milestone payments		2,400,000
Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member] | Subsequent GLA Products [Member]
Other Commitments [Line Items]
Potential future milestone payments		1,300,000
Financial Standby Letter of Credit [Member]
Other Commitments [Line Items]
Letter of credit provided as security deposit	121,000		121,000
Leasehold improvements [Member]
Other Commitments [Line Items]
Property and equipment, net				448,000
Accumulated depreciation, leasehold improvements	$22,000	$50,000	$22,000

Commitments_and_Contingencies_2

Commitments and Contingencies Commitments and Contingencies - Future Minimum Lease Payments (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
2015	$718
2016	713
2017	361
2018	372
2019	383
Total future minimum lease payments	$2,547

License_and_Collaboration_Agre1

License and Collaboration Agreements - Narrative (Details) (USD $)	12 Months Ended			1 Months Ended	51 Months Ended	8 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Aug. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Jul. 31, 2008	Dec. 31, 2009	Oct. 31, 2010
									license_agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development	$22,746,000	$11,554,000	$8,604,000
GLAAS Discovery Platform [Member] | Collaborative Arrangement, Product [Member] | Sanofi [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized				3,500,000
Milestone receivables				168,000,000
GLA [Member] | Collaborative Arrangement, Product [Member] | MedImmune LLC [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized	1,000,000				5,500,000
Number of license agreements									3
GLA [Member] | Collaborative Arrangement, Product [Member] | MedImmune LLC [Member] | Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone receivables	62,900,000				62,900,000
GLA [Member] | Collaborative Arrangement, Product [Member] | MedImmune LLC [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone receivables	75,000,000				75,000,000
GLA [Member] | Collaborative Arrangement, Product [Member] | Medicago Inc [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized						500,000
Milestone receivables	9,500,000				9,500,000
GLA [Member] | Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development	1,900,000	140,000
GLA [Member] | Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member] | Common stock [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Value of common stock issued for license							59,000
First GLA Product [Member] | Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future milestone payments	2,400,000				2,400,000
Subsequent GLA Products [Member] | Collaborative Arrangement [Member] | Infectious Disease Research Institute [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future milestone payments	1,300,000				1,300,000
Dendritic Cell-targeted Theraputic and Prophylactic Immunization Strategies [Member] | Collaborative Arrangement [Member] | California Institute of Technology [Member] | Common stock [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Value of common stock issued for license								25,000
Potential future milestone payments	1,600,000				1,600,000
Herpes Simplex Virus [Member] | Collaborative Arrangement, Product [Member] | Sanofi [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable	1,500,000				1,500,000
Unearned receivable	500,000				500,000
License Revenue [Member] | GLA [Member] | Collaborative Arrangement, Product [Member] | Sanofi [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized			805,000
Other Revenue [Member] | GLA [Member] | Collaborative Arrangement, Product [Member] | Sanofi [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized			200,000
Collaboration Revenue [Member] | Herpes Simplex Virus [Member] | Collaborative Arrangement, Product [Member] | Sanofi [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue recognized	$1,100,000

Convertible_Preferred_Stock_De

Convertible Preferred Stock (Details) (USD $)	12 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended	26 Months Ended	20 Months Ended	1 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Oct. 31, 2013	Dec. 31, 2013	Nov. 30, 2012	Dec. 31, 2012	Nov. 30, 2012	Jan. 31, 2010	Jul. 31, 2014
Class of Stock [Line Items]
Shares issued upon conversion	1
Preferred stock dividend rate	8.00%
Series C convertible preferred stock [Member]
Class of Stock [Line Items]
Issuance of convertible preferred stock (in shares)		3,951,066	3,951,066
Share price (in USD per share)		$8.18	$8.18
Proceeds from Issuance of Preferred Stock, Preference Stock, and Warrants		$32.30
Series B convertible preferred stock [Member]
Class of Stock [Line Items]
Issuance of convertible preferred stock (in shares)				1,130,165	1,130,165	3,616,529
Share price (in USD per share)			$9.41	$9.41	$9.41	$9.41
Proceeds from issuance of convertible preferred stock				10.6		34
Series A convertible preferred stock [Member]
Class of Stock [Line Items]
Issuance of convertible preferred stock (in shares)							2,201,827
Share price (in USD per share)			$8.18				$8.18
Proceeds from issuance of convertible preferred stock							$18
Convertible preferred Stock, Series C [Member]
Class of Stock [Line Items]
Number of warrants exercisable (in shares)		1,975,532
Warrant exercise price (in USD per share)		$8.18
IPO [Member] | Common stock [Member]
Class of Stock [Line Items]
Share price (in USD per share)								$12
Conversion of Stock, Shares Converted								9,769,422

Convertible_Preferred_Stock_Su

Convertible Preferred Stock Summary of Preferred Shares (Details) (USD $)	Dec. 31, 2014	Jul. 31, 2014	Dec. 31, 2013	Jan. 31, 2010	Dec. 31, 2012	Nov. 30, 2012	Oct. 31, 2013
In Thousands, except Share data, unless otherwise specified
Class of Stock [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000	12,882,593
Preferred stock, shares issued	0		9,769,422
Preferred stock, shares outstanding	0		9,769,422
Preferred stock, liquidation preference, value	$0		$84,300
Preferred stock, carrying amount	0		81,394
Series A convertible preferred stock [Member]
Class of Stock [Line Items]
Share price (in USD per share)			$8.18	$8.18
Preferred stock, shares authorized			2,201,834
Preferred stock, shares issued			2,201,827
Preferred stock, shares outstanding			2,201,827
Preferred stock, liquidation preference, value			18,000
Preferred stock, carrying amount			17,922
Series B convertible preferred stock [Member]
Class of Stock [Line Items]
Share price (in USD per share)			$9.41		$9.41	$9.41
Preferred stock, shares authorized			3,616,539
Preferred stock, shares issued			3,616,529
Preferred stock, shares outstanding			3,616,529
Preferred stock, liquidation preference, value			34,000
Preferred stock, carrying amount			33,804
Series C convertible preferred stock [Member]
Class of Stock [Line Items]
Share price (in USD per share)			$8.18				$8.18
Preferred stock, shares authorized			7,064,220
Preferred stock, shares issued			3,951,066
Preferred stock, shares outstanding			3,951,066
Preferred stock, liquidation preference, value			32,300
Preferred stock, carrying amount			$29,668

Stockholders_Equity_Deficit_Sc

Stockholders' Equity (Deficit) - Schedule of Shares of Common Stock Reserved for Future Issuance (Details)	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	3,336,378	13,331,530
Employee Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)		0
Stock Options Outstanding [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	1,907,091	1,463,747
Future Stock Grants [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	1,274,067	122,829
Convertible Preferred Stock Warrants and Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	0	1,975,532
Convertible Preferred Stock Warrants and Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	0	9,769,422

Stockholders_Equity_Deficit_Su

Stockholders' Equity (Deficit) - Summary of Stock Options (Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding, Beginning balance (in shares)	1,463,747	634,455
Options granted in period (in shares)	512,643	872,293
Options exercised in period (in shares)	-20,508	-8,499
Options cancelled in period (in shares)	-47,261	-25,141
Options expired in period (in shares)	-1,530	-9,361
Options outstanding, Ending balance (in shares)	1,907,091	1,463,747	634,455
Options vested and expected to vest (in shares)	1,781,826
Exercisable options (in shares)	790,576
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price, Beginning balance (in USD per share)	$1.20	$1.12
Weighted average exercise price of options granted in period (in USD per share)	$12.27	$1.27
Weighted average exercise price of options exercised in period (in USD per share)	$1.14	$0.69
Weighted average exercise price of options cancelled in period (in USD per share)	$3.21	$1.41
Weighted average exercise price of options expired in period (in USD per share)	$1.48	$1.26
Weighted average exercise price, Ending balance (in USD per share)	$4.16	$1.20	$1.12
Weighted average exercise price of options vested and expected to vest (in USD per share)	$3.94
Weighted average exercise price of exercisable options (in USD per share)	$1.24
Weighted average remaining contract term for outstanding options, Beginning	8 years 1 month 27 days	8 years 8 months 1 day	8 years 8 months 1 day
Weighted average remaining contract term for options vested and expected to vest	8 years 0 months 29 days
Weighted average remaining contract term for exercisable options	6 years 10 months 13 days
Aggregate intrinsic value, Beginning balance	$50,847	$2,552
Aggregate intrinsic value of options vested and expected to vest	47,885
Aggregate intrinsic value of exercisable options	$23,352

Stockholders_Equity_Deficit_Sc1

Stockholders' Equity (Deficit) - Schedule of Stock-Based Compensation Expense Recognized (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	$1,344	$255	$244
Employee [Member] | Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	421	40	30
Employee [Member] | General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	703	111	75
Non-Employee [Member] | Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	216	39	43
Non-Employee [Member] | General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Employee share-based compensation expense	$4	$65	$96

Stockholders_Equity_Deficit_Sc2

Stockholders' Equity (Deficit) - Schedule of Fair Value of Stock Options Granted to Employees (Details) (Employee Stock Option [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average estimated fair value	$9.32	$2.31	$0.97
Risk-free interest rate min	1.54%	0.97%	0.93%
Risk-free interest rate max	2.16%	1.99%	1.19%
Expected stock price volatility min	90.00%	90.00%	90.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum	93.00%	90.00%	90.00%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time to maturity	5 years 6 months 0 days	5 years 5 months 12 days	5 years 10 months 6 days
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Time to maturity	6 years 9 months 0 days	6 years 0 months 29 days	6 years 0 months 26 days

Stockholders_Equity_Deficit_Na

Stockholders' Equity (Deficit) - Narrative (Details) (USD $)	12 Months Ended			1 Months Ended	0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2014	Jan. 01, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)	16,878,817	369,460
Common stock reserved for future issuance (in shares)	3,336,378	13,331,530
Intrinsic value of stock options exercised	$243,000	$7,000	$4,000
2014 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)				1,400,000
Annual increase in common stock available for issuance (as a percent)				4.00%
Common stock authorized (in shares)	1,406,767
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)		0
Employee Stock [Member] | 2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	155,220			155,220
Annual increase in common stock available for issuance (as a percent)				1.00%
Annual increase in common stock available for issuance (in shares)				200,000
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	1,907,091	1,463,747
Unrecognized stock based compensation expense	$6,100,000
Weighted average recognition period for stock-based compensation expense	3 years 3 months 3 days
Employee Stock Option [Member] | 2008 and 2014 Equity Incentive Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term	4 years 0 months 0 days
Option expiration period	10 years 0 months 0 days
Subsequent Event [Member] | 2014 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in authorized shares					675,152
Subsequent Event [Member] | Employee Stock [Member] | 2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in authorized shares					168,788

Income_Taxes_Effective_Income_

Income Taxes Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Statutory tax rate	35.00%	35.00%
State income taxes net of federal tax benefit	0.00%	0.00%
Permanent differences	-5.09%	-2.41%
Corrections to deferred assets	0.00%	0.00%
Other	0.00%	0.35%
General business credits	2.02%	5.41%
Change in valuation allowance	-31.93%	-38.35%
Effective Income Tax Rate Reconciliation, Percent	0.00%	0.00%

Income_Taxes_Deferred_Tax_Asse

Income Taxes Deferred Tax Asset (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$29,052	$18,898
Research and development credit	2,658	1,969
Depreciation and amortization	174	174
Other temporary differences	292	232
Gross deferred tax assets	32,176	21,273
Deferred tax asset valuation allowance	-32,176	-21,273
Net deferred tax assets	$0	$0

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Tax Credit Carryforward [Line Items]
Increase in valuation allowance	$10.90	$6.10
Net operating loss carryforwards	83	54
Research Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Research and development tax credit carryforwards	$2.70	$2

Legal_Proceedings_Details

Legal Proceedings (Details) (Minimum [Member], Voluntarily Dismissed Litigation [Member], TheraVectys SA v. Immune Design Corp. [Member], USD $)	1 Months Ended
In Thousands, unless otherwise specified	Oct. 31, 2013
Minimum [Member] | Voluntarily Dismissed Litigation [Member] | TheraVectys SA v. Immune Design Corp. [Member]
Loss Contingencies [Line Items]
Claimed damages	$75

Employee_Benefit_Plan_Narrativ

Employee Benefit Plan - Narrative (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Plan Disclosure [Line Items]
Employer contribution	$153	$110	$101
Up to 3% of Employee's Compensation [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer match percentage	100.00%
Percent of employee's salary for employer match	3.00%
Between 3% and 5% of Employee's Compensation [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer match percentage	50.00%
Between 3% and 5% of Employee's Compensation [Member] | Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Percent of employee's salary for employer match	3.00%
Between 3% and 5% of Employee's Compensation [Member] | Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Percent of employee's salary for employer match	5.00%

Selected_Quarterly_Financial_I2

Selected Quarterly Financial Information (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$1,800	$3,544	$1,064	$25	$24	$129	$882	$564	$6,433	$1,599	$2,960
Net loss attributable to common stockholders	($13,120)	($6,682)	($6,126)	($8,223)	($5,406)	($3,994)	($3,634)	($2,941)	($34,151)	($15,975)	($10,840)
Basic and diluted net loss per share attributable to common stockholders (in USD per share)	($0.78)	($0.55)	($16.57)	($22.25)	($14.71)	($10.81)	($9.84)	($8.14)	($4.56)	($43.48)	($30.43)