Talphera (TLPH) 10-K 13 Mar 15 2014 FY Annual report Financial data

Document_And_Entity_Informatio

Document And Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 25, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	ACELRX PHARMACEUTICALS INC
Document Type	10-K
Current Fiscal Year End Date	-19
Entity Common Stock, Shares Outstanding		43,714,665
Entity Public Float			$318,700,000
Amendment Flag	FALSE
Entity Central Index Key	1427925
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY

Balance_Sheets

Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current Assets:
Cash and cash equivalents	$60,038	$88,401
Short-term investments	15,312	15,262
Prepaid expenses and other current assets	948	897
Total current assets	76,298	104,560
Property and equipment, net	9,818	5,179
Restricted cash	250	250
Other assets	81	42
Total Assets	86,447	110,031
Current Liabilities:
Accounts payable	2,431	2,341
Accrued liabilities	3,654	3,904
Deferred revenue, current portion	787	623
Long-term debt, current portion	6,859
Total current liabilities	13,731	6,868
Deferred rent	529	188
Long-term debt, net of current portion	18,046	14,364
Deferred revenue, net of current portion	1,626	2,007
Contingent put option liability	282	334
Warrant liability	5,577	13,111
Total liabilities	39,791	36,872
Stockholders’ Equity:
Common stock, $0.001 par value—100,000,000 shares authorized as of December 31, 2014 and 2013; 43,712,363 and 43,050,580 shares issued and outstanding as of December 31, 2014 and 2013	43	43
Additional paid-in capital	225,423	218,568
Accumulated deficit	-178,806	-145,453
Accumulated other comprehensive income (loss)	-4	1
Total stockholders’ equity	46,656	73,159
Total Liabilities and Stockholders’ Equity	$86,447	$110,031

Balance_Sheets_Parentheticals

Balance Sheets (Parentheticals) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Common stock, par value (in Dollars per share)	$0.00	$0.00
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	43,712,363	43,050,580
Common stock, shares outstanding	43,712,363	43,050,580

Statements_of_Comprehensive_Lo

Statements of Comprehensive Loss (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue:
Collaboration agreement	$5,217	$27,370
Research grant	0	2,132	2,394
Total revenue	5,217	29,502	2,394
Operating expenses:
Research and development	24,520	26,292	24,908
General and administrative	18,346	9,877	7,199
Total operating expenses	42,866	36,169	32,107
Loss from operations	-37,649	-6,667	-29,713
Interest expense	-2,639	-1,518	-2,283
Interest income and other income (expense), net	6,935	-15,241	-1,367
Net loss	-33,353	-23,426	-33,363
Other comprehensive income (loss):
Unrealized gains (losses) on available for sale securities	-5		1
Comprehensive loss	($33,358)	($23,426)	($33,362)
Net loss per share of common stock, basic (in Dollars per share)	($0.77)	($0.59)	($1.51)
Net loss per share of common stock, diluted (in Dollars per share)	($0.91)	($0.59)	($1.51)
Shares used in computing net loss per share of common stock, basic (in Shares)	43,427,111	39,746,678	22,124,637
Shares used in computing net loss per share of common stock, diluted –see Note 11 (in Shares)	44,322,297	39,746,678	22,124,637

Statements_of_Stockholders_Equ

Statements of Stockholders' Equity (Deficit) (USD $)	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
In Thousands, except Share data
Balance at Dec. 31, 2011	$22	$106,110	($88,664)		$17,468
Balance (in Shares) at Dec. 31, 2011	19,567,778
Stock-based compensation		2,150			2,150
Issuance of common stock upon exercise of stock options and in connection with restricted stock units		80			80
Issuance of common stock upon exercise of stock options and in connection with restricted stock units (in Shares)	122,108
Issuance of common stock upon ESPP purchase		169			169
Issuance of common stock upon ESPP purchase (in Shares)	67,804
Issuance of common stock upon private placement offering, net of offering-related costs of $0.9 million	1	3,245			3,246
Issuance of common stock upon private placement offering, net of offering-related costs of $0.9 million (in Shares)	2,922,337
Issuance of common stock upon underwritten public offering, net of offering-related costs	14	44,082			44,096
Issuance of common stock upon underwritten public offering, net of offering-related costs (in Shares)	14,375,000
Change in unrealized gains and losses on investments, net of taxes				1	1
Net loss			-33,363		-33,363
Balance at Dec. 31, 2012	37	155,836	-122,027	1	33,847
Balance (in Shares) at Dec. 31, 2012	37,055,027
Stock-based compensation		3,479			3,479
Issuance of common stock upon exercise of stock options and in connection with restricted stock units	1	1,276			1,277
Issuance of common stock upon exercise of stock options and in connection with restricted stock units (in Shares)	520,365
Issuance of common stock upon exercise of stock warrants	1	8,689			8,690
Issuance of common stock upon exercise of stock warrants (in Shares)	1,050,062				808,078
Issuance of common stock upon ESPP purchase		219			219
Issuance of common stock upon ESPP purchase (in Shares)	55,126
Issuance of common stock upon underwritten public offering, net of offering-related costs	4	47,939			47,943
Issuance of common stock upon underwritten public offering, net of offering-related costs (in Shares)	4,370,000
Net loss			-23,426		-23,426
Issuance of Warrants		1,130			1,130
Balance at Dec. 31, 2013	43	218,568	-145,453	1	73,159
Balance (in Shares) at Dec. 31, 2013	43,050,580
Stock-based compensation		4,440			4,440
Issuance of common stock upon exercise of stock options and in connection with restricted stock units		1,507			1,507
Issuance of common stock upon exercise of stock options and in connection with restricted stock units (in Shares)	487,124
Issuance of common stock upon exercise of stock warrants		546			546
Issuance of common stock upon exercise of stock warrants (in Shares)	91,488				91,488
Issuance of common stock upon ESPP purchase		362			362
Issuance of common stock upon ESPP purchase (in Shares)	83,171
Change in unrealized gains and losses on investments, net of taxes				-5	-5
Net loss			-33,353		-33,353
Balance at Dec. 31, 2014	$43	$225,423	($178,806)	($4)	$46,656
Balance (in Shares) at Dec. 31, 2014	43,712,363

Statements_of_Stockholders_Equ1

Statements of Stockholders' Equity (Deficit) (Parentheticals) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Issuance of common stock upon private placement, offering-related costs		$900
Issuance of common stock, offering-related costs	$3,000	$3,500

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
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	($33,353)	($23,426)	($33,363)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	866	593	605
Amortization of premium/discount on investments, net	216	202	380
Interest expense related to debt financing	553	442	647
Stock-based compensation	4,440	3,479	2,150
Revaluation of put option and PIPE warrant liabilities	-7,040	14,071	1,439
Loss on extinguishment of debt		1,202
Other			43
Changes in operating assets and liabilities:
Prepaid expenses and other assets	137	1,132	429
Restricted cash		-45
Accounts payable	90	106	705
Accrued liabilities	-126	-760	2,029
Deferred revenue	-217	2,630
Deferred rent	-22	-113	354
Net cash used in operating activities	-34,456	-487	-24,582
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	-5,505	-3,287	-826
Purchase of investments	-17,430	-28,009	-27,167
Proceeds from maturities of investments	17,159	24,376	42,948
Net cash provided by (used in) investing activities	-5,776	-6,920	14,955
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock in equity offerings, net of offering costs		47,943	53,174
Proceeds from the issuance of long-term debt	10,000	14,958
Payment of long-term debt		-16,345	-3,655
Extinguishment of debt		-437
Net proceeds from issuance of common stock through equity plans and exercise of warrants	1,869	1,757	246
Net cash provided by financing activities	11,869	47,876	49,765
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	-28,363	40,469	40,138
CASH AND CASH EQUIVALENTS—Beginning of period	88,401	47,932	7,794
CASH AND CASH EQUIVALENTS—End of period	60,038	88,401	47,932
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	1,752	1,105	1,632
NONCASH INVESTING AND FINANCING ACTIVITIES:
Issuance of common stock upon cashless exercise of warrants	546	8,428
Issuance of warrants for common stock		1,130	5,828
Tenant improvement allowance receivable	239
Contingent put option liability		334
Purchases of property and equipment in Accounts payable	182
Purchases of property and equipment in Accrued liabilities	$23	$725

Note_1_Organization_and_Summar

Note 1 - Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	1. Organization and Summary of Significant Accounting Policies
	The Company
	AcelRx Pharmaceuticals, Inc., or the Company or AcelRx, was incorporated in Delaware on July 13, 2005 as SuRx, Inc., and in January 2006, the Company changed its name to AcelRx Pharmaceuticals, Inc. The Company’s operations are based in Redwood City, California.
	AcelRx is a specialty pharmaceutical company focused on the development and commercialization of innovative therapies for the treatment of acute pain. AcelRx intends to commercialize its product candidates in the United States and license the development and commercialization rights to its product candidates for sale outside of the United States through strategic partnerships and collaborations. On July 25, 2014, the U.S. Food and Drug Administration, or FDA, issued a Complete Response Letter, or CRL, for the Company’s new drug application, or NDA, for Zalviso™ (sufentanil sublingual tablet system), formerly known as ARX-01. In March 2015, the Company announced the receipt of correspondence from the FDA stating that in addition to the bench testing and two Human Factors studies it has performed, an additional clinical study is needed to assess the risk of inadvertent dispensing and overall risk of dispensing failures. The proposed indication for Zalviso is for the management of moderate-to-severe acute pain in adult patients in the hospital setting. Zalviso consists of sufentanil sublingual tablets delivered by the Zalviso System, a needle-free, handheld, patient-administered, pain management system (together, “Zalviso”).
	The Company has incurred recurring operating losses and negative cash flows from operating activities since inception and expects to continue to incur negative cash flows until its product candidates are approved for marketing in the United States and other countries, in which it has and intends to license its products, which may never occur. In previous years, prior to the completion of the clinical development program for Zalviso and the commercial collaboration of Zalviso, AcelRx was considered a development stage company.
	The Company has one business activity, which is the development and commercialization of product candidates for the treatment of pain, and a single reporting and operating unit structure.
	Basis of Presentation
	The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. Actual results could differ from those estimates.
	Use of Estimates
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Management evaluates its estimates on an ongoing basis including critical accounting policies. Estimates are based on historical experience and on various other market-specific and other relevant assumptions that the Company believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates.
	Concentration of Risk
	The Company invests cash that is currently not being used for operational purposes in accordance with its investment policy in debt securities of the U.S. Treasury and U.S. government sponsored agencies and overnight deposits. The Company is exposed to credit risk in the event of default by the institutions holding the cash equivalents and available-for-sale securities to the extent recorded on the balance sheet. Our cash and cash equivalent balances can be in excess of federally
	insured amounts.
	Cash, Cash Equivalents and Marketable Securities
	The Company considers all highly liquid investments with an original maturity (at date of purchase) of three months or less to be cash equivalents. Cash and cash equivalents consist of cash on deposit with banks and money market instruments.
	All marketable securities are classified as available-for-sale and consist of U.S. Treasury and U.S. government sponsored enterprise debt securities. These securities are carried at estimated fair value, which is based on quoted market prices or observable market inputs of almost identical assets, with unrealized gains and losses included in accumulated other comprehensive income (loss). The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income or expense. The cost of securities sold is based on specific identification. The Company’s investments are subject to a periodic impairment review for other-than-temporary declines in fair value. The Company’s review includes the consideration of the cause of the impairment including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. When the Company determines that the decline in fair value of an investment is below its accounting basis and this decline is other-than-temporary, it reduces the carrying value of the security it holds and records a loss in the amount of such decline.
	Property and Equipment
	Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the estimated useful life of the improvements or the remaining lease term.
	Impairment of Long-Lived Assets
	The Company periodically assesses the impairment of long-lived assets and, if indicators of asset impairment exist, the Company assesses the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through an analysis of the undiscounted future expected operating cash flows. If impairment is indicated, the Company records the amount of such impairment for the excess of the carrying value of the asset over its estimated fair value. For example, purchased equipment and manufacturing-related facility improvements the Company has made at Patheon’s facility in Ohio, are utilized for continued research and development, and potential commercial manufacturing of our product candidates. If the Company does not receive regulatory approval for our product candidates, the Company may determine that it is no longer probable that the Company will realize the future economic benefit associated with the costs of these assets through future manufacturing activities, and if so, the Company would record an impairment charge associated with these assets. As of December 31, 2014, the Company has not written down any of its long-lived assets as a result of impairment.
	Restricted Cash
	Under the Company’s facility lease and corporate credit card agreements, the Company is required to maintain letters of credit as security for performance under these agreements. The letters of credit are secured by certificates of deposit in amounts equal to the letters of credit, which are classified as restricted cash on the balance sheet.
	Contingent put option
	The contingent put option associated with the Company’s loan and security agreement with Hercules Technology II, L.P. and Hercules Technology Growth Capital, Inc., collectively referred to as Hercules, is recorded as a liability. Changes in the fair value of the contingent put option are recognized as interest income and other income (expense), net in the Statements of Comprehensive Loss. For additional information regarding the contingent put option, see Note 6 “Long Term Debt.”
	Warrants
	Warrants issued in connection with the Company’s Private Placement, completed in June 2012, are recorded as liabilities as they have the potential for cash settlement upon the occurrence of certain transactions (as defined in the warrant; see Note 7 “Warrants”). Changes in the fair value of the warrants are recognized as interest income and other income (expense), net in the Statements of Comprehensive Loss.
	Revenue Recognition
	The Company recognizes revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the fee is fixed or determinable; and collectability is reasonably assured.
	Collaboration Revenue
	Collaboration revenue, which is earned under license agreements with third parties, may include nonrefundable license fees, cost reimbursements, research and development services, commercial manufacturing services, contingent development and commercial milestones and royalties.
	AcelRx accounts for multiple-element arrangements in accordance with ASC Topic 605-25, Revenue Recognition—Multiple-Element Arrangements, or ASC 605-25.The Company evaluates if the deliverables in the arrangement represent separate units of accounting. In determining the units of accounting, AcelRx evaluates certain criteria, including whether the deliverables have value to our customers on a stand-alone basis. Factors considered in this determination include whether the deliverable is proprietary to the Company, whether the customer can use the license or other deliverables for their intended purpose without the receipt of the remaining elements, whether the value of the deliverable is dependent on the undelivered items, and whether there are other vendors that can provide the undelivered items. Deliverables that meet these criteria are considered a separate unit of accounting. Deliverables that do not meet these criteria are combined and accounted for as a single unit of accounting.
	For revenue agreements with multiple-element arrangements, such as the collaboration and license agreement with Grünenthal, the Company allocates revenue to each non-contingent element based on the relative selling price of each element. When applying the relative selling price method, the Company determines the selling price for each deliverable using vendor-specific objective evidence, or VSOE, of selling price or third-party evidence, or TPE, of selling price. If neither exists the Company uses best estimated selling price, or BESP, for that deliverable. Revenue allocated is then recognized when the four basic revenue recognition criteria are met for each element.
	VSOE is based on the price charged when the element is sold separately and is the price actually charged for that deliverable. Establishing VSOE may not be possible for the elements of a license arrangement because each arrangement is unique, an arrangement typically consists of multiple elements and AcelRx has limited history of entering into license arrangements. When VSOE cannot be established, AcelRx attempts to establish the selling price of the elements of a license arrangement based on TPE. TPE is determined based on a competitor’s price for similar deliverables when sold separately. AcelRx may not be able to determine TPE for license arrangements, as they contain a significant level of differentiation such that the comparable pricing of a competitor’s license arrangement with similar functionality cannot be obtained, and AcelRx is therefore unable to reliably determine what a similar competitor’s license arrangement’s selling price would be on a standalone basis.
	When AcelRx is unable to establish the selling price of an element using VSOE or TPE, BESP is utilized in the allocation of the elements of the arrangement. The objective of the BESP is to determine the price at which AcelRx would transact a sale if the element of the license arrangement were sold on a standalone basis.
	The process for determining BESPs involves management’s judgment. AcelRx’ process considers multiple factors such as discounted cash flows, estimated direct expenses and other costs and available data, which may vary over time, depending upon the circumstances, and relate to each deliverable. If the estimated obligation period of one or more deliverables should change, the future amortization of the revenue would also change.
	AcelRx recognizes a contingent milestone payment as revenue in its entirety upon our achievement of the milestone. A milestone is substantive if the consideration earned from the achievement of the milestone (i) is consistent with performance required to achieve the milestone or the increase in value to the delivered item, (ii) relates solely to past performance and (iii) is reasonable relative to all of the other deliverables and payments within the arrangement.
	Research Grant Revenue
	In May 2011, the Company entered into an award contract with the US Army Medical Research and Materiel Command, or USAMRMC, to support the development of the Company’s new product candidate, ARX-04, a sufentanil sublingual tablet for the treatment of moderate-to-severe acute pain. The grant provides for the reimbursement of qualified expenses for research and development activities as defined under the terms of the grant agreement. Revenue under the grant agreement is recognized when the related qualified research expenses are incurred.
	Research and Development Expenses
	Research and development costs are charged to expense when incurred. Research and development expenses include salaries, employee benefits, including stock-based compensation, consultant fees, laboratory supplies, costs associated with clinical trials and manufacturing, including contract research organization fees, other professional services and allocations of corporate costs. The Company reviews and accrues clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of patient studies and other events.
	Comprehensive Loss
	Comprehensive loss is comprised of net loss and other comprehensive income (loss) and is disclosed in the Statement of Comprehensive Loss. For the Company, other comprehensive income (loss) consists of changes in unrealized gains and losses on the Company’s investments.
	Fair Value of Financial Instruments
	The Company measures and reports its cash equivalents, investments and financial liabilities at fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability 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 fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows:
	Level I—Unadjusted quoted prices in active markets for identical assets or liabilities;
	Level II—Inputs other than quoted prices included within Level I that are observable, unadjusted 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 related assets or liabilities; and
	Level III—Unobservable inputs that are supported by little or no market activity for the related assets or liabilities.
	The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.
	Income Taxes
	Deferred tax assets and liabilities are measured based on differences between the financial reporting and tax basis of assets and liabilities using enacted rates and laws that are expected to be in effect when the differences are expected to reverse. The Company records a valuation allowance for the full amount of deferred assets, which would otherwise be recorded for tax benefits relating to operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not.
	Stock-Based Compensation
	Compensation expense for all share-based payment awards made to employees and directors, including employee stock options, restricted stock units and employee share purchases related to the 2011 Employee Stock Purchase Plan, or ESPP, is based on estimated fair values at grant date. The Company determines the grant date fair value of the awards using the Black-Scholes option-pricing model and generally recognizes the fair value as stock-based compensation expense on a straight-line basis over the vesting period of the respective awards.
	The Black-Scholes option pricing model requires inputs such as expected term, expected volatility and risk-free interest rate. These inputs are subjective and generally require significant analysis and judgment to develop. Estimates of expected life are primarily determined using the simplified method in accordance with guidance provided by the SEC. Such method was utilized as the Company did not believe its historical option exercise experience, which was limited, provided a reasonable basis upon which to estimate expected term. Volatility is derived from historical volatilities of several public companies within AcelRx’s industry that are deemed to be comparable to AcelRx’s business because AcelRx’s has insufficient history on the volatility of its common stock relative to the expected life assumptions used by the Company. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant commensurate with the expected life assumption. Further, the Company estimates forfeitures at the time of grant and revises those estimates in subsequent periods if actual forfeitures differ from those estimates.
	Net Loss per Share of Common Stock
	The Company’s basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. The diluted net loss per share of common stock is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, convertible preferred stock, options to purchase common stock, restricted stock subject to repurchase, warrants to purchase convertible preferred stock and warrants to purchase common stock were considered to be common stock equivalents. In periods with a reported net loss, such common stock equivalents are excluded from the calculation of diluted net loss per share of common stock if their effect is antidilutive. For additional information regarding the net loss per share, see Note 11 “Net Loss per Share of Common Stock.”
	Segment Information
	The Company operates in one operating segment and has operations solely in the United States.
	Recently Issued Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU 2014-15 will explicitly require management to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosure in certain circumstances. The new standard will be effective for AcelRx beginning in fiscal 2017. Earlier adoption is permitted. The Company is currently evaluating the potential impact of the adoption of ASU 2014-15.
	In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, issued as a new Topic, Accounting Standards Codification (ASC) Topic 606.  The new revenue recognition standard provides a five-step analysis of transactions to determine when and how revenue is recognized. The core principle of the guidance is that a Company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This ASU is effective for AcelRx beginning in fiscal 2017 and can be adopted by the Company either retrospectively or as a cumulative-effect adjustment as of the date of adoption.  The Company is currently evaluating the effect that adopting this new accounting guidance will have on its results of operations, cash flows and financial position.

Note_2_Investments_and_Fair_Va

Note 2 - Investments and Fair Value Measurement	12 Months Ended
	Dec. 31, 2014
Investments And Fair Value Measurement Disclosure [Abstract]
Investments And Fair Value Measurement Disclosure [Text Block]	2. Investments and Fair Value Measurement
	Investments
	The Company classifies its marketable securities as available-for-sale and records its investments at fair value. Available-for-sale securities are carried at estimated fair value based on quoted market prices or observable market inputs of almost identical assets, with the unrealized holding gains and losses included in accumulated other comprehensive income. Marketable securities which have maturities beyond one year as of the end of the reporting period are classified as non-current.
	The table below summarizes the Company’s cash, cash equivalents and investments (in thousands):
		As of December 31, 2014
		Amortized Cost			Gross Unrealized			Gross Unrealized			Fair
					Gains			Losses			Value
	Cash and cash equivalents:
	Cash	$	60,005		$	—		$	—		$	60,005
	Money market funds		33			—			—			33
	Total cash and cash equivalents		60,038			—			—			60,038
	Marketable securities:
	U.S. government agency securities		15,316			—			(4	)		15,312
	Total marketable securities		15,316			—			(4	)		15,312
	Total cash, cash equivalents and investments	$	75,354		$	—		$	(4	)	$	75,350
		As of December 31, 2013
		Amortized Cost			Gross Unrealized			Gross Unrealized			Fair
					Gains			Losses			Value
	Cash and cash equivalents:
	Cash	$	88,390		$	—		$	—		$	88,390
	Money market funds		11			—			—			11
	Total cash and cash equivalents		88,401			—			—			88,401
	Marketable securities:
	U.S. government agency securities		15,261			1			—			15,262
	Total marketable securities		15,261			1			—			15,262
	Total cash, cash equivalents and investments	$	103,662		$	1		$	—		$	103,663
	None of the available-for-sale securities held by the Company had material unrealized losses and there were no realized losses for the years ended December 31, 2014 and 2013. There were no other-than-temporary impairments for these securities as of December 31, 2014 or 2013.
	As of December 31, 2014 and 2013, the contractual maturity of all investments held was less than one year.
	Fair Value Measurement
	The Company’s financial instruments consist of Level I and Level II assets and Level III liabilities. Level I securities include highly liquid money market funds and are valued based on quoted market prices. For Level II instruments, the Company estimates fair value by utilizing third party pricing services in developing fair value measurements where fair value is based on valuation methodologies such as models using observable market inputs, including benchmark yields, reported trades, broker/dealer quotes, bids, offers and other reference data. Such Level II instruments typically include U.S. treasury and U.S. government agency obligations. As of December 31, 2014 and December 31, 2013, the Company held, in addition to Level I and Level II assets, a contingent put option liability associated with the Company’s loan and security agreement with Hercules Technology II, L.P. and Hercules Technology Growth Capital, Inc., collectively referred to as Hercules, which was classified as a Level III liability. The Company’s estimate of fair value of the contingent put option liability was determined by using a risk-neutral valuation model, wherein the fair value of the underlying debt facility is estimated both with and without the presence of the default provisions, holding all other assumptions constant. The resulting difference between the two estimated fair values is the estimated fair value of the default provisions, or the contingent put option. The fair value of the underlying debt facility is estimated by calculating the expected cash flows in consideration of an estimated probability of default and expected recovery rate in default, and discounting such cash flows back to the reporting date using a risk-free rate. As of December 31, 2014 and 2013, the Company also held a Level III liability associated with warrants, or PIPE warrants, issued in connection with the Company’s private placement equity offering, completed in June 2012. For a detailed description, see Note 9 “Stockholders’ Equity.” The PIPE warrants are considered a liability and are valued using the Black-Scholes option-pricing model, the inputs for which include exercise price of the PIPE warrants, market price of the underlying common shares, expected term, volatility based on a group of the Company’s peers and the risk-free rate corresponding to the expected term of the PIPE warrants. Changes to any of these inputs can have a significant impact to the estimated fair value of the PIPE warrants.
	The following table sets forth the fair value of the Company’s financial assets and liabilities by level within the fair value hierarchy (in thousands):
		As of December 31, 2014
		Fair Value			Level I			Level II			Level III
	Assets
	Money market funds	$	33		$	33		$	—		$	—
	U.S. government agency obligations		15,312			—			15,312			—
	Total assets measured at fair value	$	15,345		$	33		$	15,312		$	—
	Liabilities
	PIPE warrant	$	5,577		$	—		$	—		$	5,577
	Contingent put option		282			—			—			282
	Total liabilities measured at fair value	$	5,859		$	—		$	—		$	5,859
		As of December 31, 2013
		Fair Value			Level I			Level II			Level III
	Assets
	Money market funds	$	11		$	11		$	—		$	—
	U.S. government agency obligations		15,262			—			15,262			—
	Total assets measured at fair value	$	15,273		$	11		$	15,262		$	—
	Liabilities
	PIPE warrant	$	13,111		$	—		$	—		$	13,111
	Contingent put option		334			—			—			334
	Total liabilities measured at fair value	$	13,445		$	—		$	—		$	13,445
	The following table sets forth the assumptions used in the Black-Scholes option-pricing model to estimate the fair value of the PIPE warrants as of December 31, 2014 and 2013:
		As of December 31,			As of December 31,
		2014			2013
	Market Price	$	6.73		$	11.31
	Exercise Price	$	3.4		$	3.4
	Risk-free interest rate		1.1	%		1.27	%
	Expected volatility		61	%		69	%
	Expected life (in years)		2.92			3.92
	Expected dividend yield		0	%		0	%
	The following table sets forth a summary of the changes in the fair value of the Company’s Level III financial liabilities for the years ended December 31, 2014 and 2013 (in thousands):
		Year Ended
		December 31,
		2014
Fair value—beginning of period	$	13,445
Change in fair value of PIPE warrants		(7,534	)
Change in fair value of contingent put option associated with Amended Loan Agreement with Hercules		(52	)
Fair value—end of period	$	5,859
	Year Ended
	December 31,
	2013
Fair value—beginning of period	$	7,500
Change in fair value of PIPE warrants		5,693
Change in fair value of contingent put option associated with 2011 loan and security agreement with Hercules		(82	)
Addition of contingent put option associated with 2013 loan and security agreement with Hercules		334
Fair value—end of period	$	13,445

Note_3_Property_and_Equipment

Note 3 - Property and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	3. Property and Equipment
	Property and equipment consist of the following (in thousands):
		As of December 31,
		2014			2013
	Research equipment	$	2,549		$	2,014
	Leasehold improvements		4,469			1,425
	Computer equipment and software		334			189
	Construction in process		4,844			3,277
	Tooling		527			318
	Furniture and fixtures		50			59
			12,773			7,282
	Less accumulated depreciation and amortization		(2,955	)		(2,103	)
	Property and equipment, net	$	9,818		$	5,179
	Depreciation and amortization expense was $0.9 million, $0.6 million and $0.5 million during the years ended December 31, 2014, 2013 and 2012, respectively. Property and equipment, net in the balance sheet at December 31, 2014, includes $3.8 million related to certain modifications the Company has made at Patheon Pharmaceutical Inc.’s, or Patheon’s, Cincinnati facility under the terms of the Capital Expenditure and Equipment Agreement, or the Capital Agreement.

Note_4_Research_Grant

Note 4 - Research Grant	12 Months Ended
	Dec. 31, 2014
Research and Development [Abstract]
Research, Development, and Computer Software Disclosure [Text Block]	4. Research Grant
	In May 2011, AcelRx received a grant from the US Army Medical Research and Materiel Command, or USAMRMC, in which the USAMRMC granted $5.6 million to the Company in order to support the development of a new product candidate, ARX-04, a sufentanil sublingual tablet for the treatment of moderate-to-severe acute pain. Under the terms of the grant, the USAMRMC will reimburse the Company for development, manufacturing and clinical costs necessary to prepare for and complete the planned Phase 2 dose-finding trial in a study of acute moderate-to-severe pain, and to prepare to enter Phase 3 development. The grant gives the USAMRMC the option to extend the term of the grant and provide additional funding for the research. As of December 31, 2013, the full amount of the grant, $5.6 million, had been recognized as revenue.
	Revenue is recognized based on expenses incurred by AcelRx in conducting research and development activities set forth in the agreement. Revenue attributable to the research and development performed under the USAMRMC grant was $0, $2.1 million and $2.4 million for the years ended December 31, 2014, 2013, and 2012, respectively.

Note_5_Collaboration

Note 5 - Collaboration	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Arrangement Disclosure [Text Block]	5. Collaboration
	On December 16, 2013, AcelRx and Grünenthal GmbH, or Grünenthal, entered into a Collaboration and License Agreement, or the License Agreement, and related Manufacture and Supply Agreement, or the Manufacturing Agreement, and together with the License Agreement, or the Agreements. The License Agreement grants Grünenthal rights to commercialize Zalviso the Company’s novel sublingual patient-controlled analgesia, or PCA, system, or the Product, in the countries of the European Union, Switzerland, Liechtenstein, Iceland, Norway and Australia, or the Territory, for human use in pain treatment within or dispensed by hospitals hospices, nursing homes and other medically-supervised settings, or the Field. The Company retains rights with respect to the Product in countries outside the Territory, including the United States, Asia and Latin America. Under the Supply Agreement, the Company will exclusively manufacture and supply the Product to Grünenthal for the Field in the Territory.
	License Agreement
	Under the terms of the License Agreement, Grünenthal has the exclusive right to commercialize the Product in the Field in the Territory. The Company retains control of clinical development, while Grünenthal and the Company will be responsible for certain development activities pursuant to a development plan as agreed between the parties. The Company will not receive separate payment for such development activities. Grünenthal is exclusively responsible for marketing approval applications and other regulatory filings relating to the sufentanil sublingual tablet drug cartridge for the Product in the Field in the Territory, while the Company is responsible for the CE Mark and other regulatory filings relating to device portions of the Product. A CE Mark (#611742) for Zalviso was obtained in the fourth quarter 2014 which specifies AcelRx as the device design authority and manufacturer.
	The Company received an upfront non-refundable cash payment of $30.0 million in December 2013, and a milestone payment of $5.0 million related to the MAA submission in the third quarter of 2014. The Company is eligible to receive an additional $15.0 million milestone payment upon the approval of the MAA, if approved. If the MAA is approved, the Company is eligible to receive approximately $200.0 million in additional milestone payments, based upon successful regulatory and product development efforts ($28.5 million) and net sales target achievements ($171.5 million). Grünenthal will also make tiered royalty and supply and trademark fee payments in the mid-teens up to the mid-twenties percent range on net sales of Zalviso.
	Unless earlier terminated, the License Agreement continues in effect until the expiration of the obligation of Grünenthal to make royalty and supply and trademark fee payments, which supply and trademark fee continues for so long as the Company continues to supply the Product to Grünenthal. The License Agreement is subject to earlier termination in the event the parties mutually agree, by a party in the event of an uncured material breach by the other party, upon the bankruptcy or insolvency of either party, or by Grünenthal for convenience.
	Manufacturing Agreement
	Under the terms of the Manufacturing Agreement, the Company will manufacture and supply the Product for use in the Field for the Territory exclusively for Grünenthal. Grünenthal shall purchase from AcelRx, during the first five years after the effective date of the Manufacturing Agreement, 100% and thereafter 80% of Grünenthal’s and its sublicensees’ and distributors’ requirements of Product for use in the Field for the Territory. The Product will be supplied at the Company’s fully burdened manufacturing cost (as defined in the Manufacturing Agreement). The Manufacturing Agreement requires the Company to use commercially reasonable efforts to enter stand-by contracts with third parties providing significant supply and manufacturing services and under certain specified conditions permits Grünenthal to use a third party back-up manufacturer to manufacture the Product for Grünenthal’s commercial sale in the Territory.
	Unless earlier terminated, the Manufacturing Agreement continues in effect until the later of the expiration of the obligation of Grünenthal to make royalty and supply and trademark fee payments or the end of any transition period for manufacturing obligations due to the expiration or termination of the License Agreement. The Manufacturing Agreement is subject to earlier termination in connection with certain termination events in the License Agreement, in the event the parties mutually agree, by a party in the event of an uncured material breach by the other party or upon the bankruptcy or insolvency of either party.
	The Company identified the following four significant non-contingent performance deliverables under the agreements: 1) intellectual property (license), 2) the obligation to provide research and development services, 3) the significant and incremental discount on the manufacturing of Zalviso for commercial purposes, and 4) the obligation to participate on the joint steering committee.
	The Company considered the provisions of the multiple-element arrangement guidance in determining whether the deliverables outlined above have standalone value and thus should be treated as separate units of accounting. Company’s management determined that the license has standalone value and represents a separate unit of accounting because the rights conveyed permit Grünenthal to perform all efforts necessary to commercialize and begin selling the product upon regulatory approval. In addition, Grünenthal has the appropriate development, regulatory and commercial expertise with products similar to the product licensed under the agreement and has the ability to engage third parties to manufacture the product allowing Grünenthal to realize the value of the license without receiving any of the remaining deliverables. Grünenthal can also sublicense its license rights to third parties. Also, the Company’s management determined that the research services, committee participation and implied discount associated with the manufacturing services each represent individual units of accounting as Grünenthal could perform such services and/or could acquire these on a separate basis.
	The Company developed best estimates of selling prices for each deliverable in order to allocate the noncontingent arrangement consideration to the four units of accounting.
	The Company’s management determined the best estimate of selling price for the license based on Grünenthal’s estimated future cash flows arising from the arrangement. Embedded in the estimate were significant assumptions regarding regulatory expenses, revenue, including potential customer market for the product and product price, costs to manufacture the product and the discount rate. The Company’s management determined the best estimate of selling price of the research and development services and committee participation based on the nature and timing of the services to be performed and in consideration of personnel and other costs incurred in the delivery of the services. For the discount on manufacturing services, Company’s management estimated the selling price based on the market level of contract manufacturing margin it could have received if it were engaged to supply products to a customer in a separate transaction.
	The Agreements entitle the Company to receive additional payments upon the achievement of certain development and sales milestones. Based on ASC Topic 605-28, Revenue Recognition — Milestone Method, the Company evaluates contingent milestones at inception of the agreement, and recognizes consideration that is contingent upon the achievement of a milestone in its entirety as revenue in the period in which the milestone is achieved only if the milestone is considered substantive in its entirety. Milestones are events which have the following characteristics: (i) they can be achieved based in whole or in part on either the Company’s performance or on the occurrence of a specific outcome resulting from the Company’s performance, (ii) there was substantive uncertainty at the date the agreement was entered into that the event would be achieved and, (iii) they would result in additional payments due to the Company. A milestone is considered substantive if the following criteria are met: (i) the consideration is commensurate with either (1) the entity’s performance to achieve the milestone, or (2) the enhancement of the value of the delivered item (s) as a result of a specific outcome resulting from the entity’s performance to achieve the milestone, (ii) the consideration relates solely to past performance and, (iii) the consideration is reasonable relative to all of the other deliverables and payment terms, including other potential milestone consideration, within
	the arrangement.
	The substantive milestone payments will be recognized as revenue in their entirety upon the achievement of each substantive milestone. Based on the criteria noted above, the identified substantive milestones in the agreement pertain to post approval product enhancements, expanded market opportunities and manufacturing efficiencies for Zalviso. Each of these potential achievements is based primarily on the Company’s performance and involves substantive uncertainty as achievement of these milestones require future research, development and regulatory activities, which are inherently uncertain in nature. The Company determined that the consideration for each milestone was commensurate with the Company’s performance to achieve the milestone, including future research, development, manufacturing and regulatory activities and that the consideration is reasonable relative to all of the other deliverables and payments within the arrangement. Aggregate potential payments for these milestones total $28.5 million.
	In addition to substantive milestones, two milestones associated with the Agreements were deemed not to be substantive. These milestones pertain to regulatory developments for Zalviso in Europe, which Company’s management deemed to be not substantive due to the level of performance associated with future achievement of these milestones. Aggregate potential payments for these milestones total $20.0 million. In July 2014, Grünenthal submitted a Marketing Authorization Application, or MAA, to the European Medicines Agency, or EMA, for Zalviso for the management of moderate-to-severe acute pain in adult patients in a medically supervised environment. Under the terms of the License Agreement with Grünenthal, the Company received a cash payment of $5.0 million for the MAA submission in the third quarter of 2014. The Company is eligible to receive an additional $15.0 million milestone payment upon the approval of the MAA.
	The Agreements also include milestone payments related to specified net sales targets, totaling $171.5 million. The sales-based milestones do not meet the definition of a milestone under ASU 2010-17 because the achievement of these milestones is solely dependent on counter-party performance and not on any performance obligations of the Company.
	The Company allocated the $30.0 million upfront fee across the four deliverables based on estimated selling prices and during the year ended December 31, 2013, recognized $27.4 million attributable to the license. As mentioned above, the Company received a milestone payment of $5.0 million related to the MAA submission, of which $4.6 million was recognized during the year ended December 31, 2014. In addition, the Company recognized $0.6 million of previously deferred revenue related to research and development services and its obligation to participate in the joint steering committee under the collaboration agreement during the year ended December 31, 2014. As of December 31, 2014, the Company had a deferred revenue balance of $2.4 million. There were no other milestone payments received or recognized under these Agreements during the year ended December 31, 2014.

Note_6_Longterm_Debt

Note 6 - Long-term Debt	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Long-term Debt [Text Block]	6. Long-Term Debt
	Hercules Loan and Security Agreements
	In June 2011, AcelRx entered into a loan and security agreement with Hercules, under which AcelRx borrowed $20.0 million in two tranches of $10.0 million each, represented by secured convertible term promissory notes. The Company’s obligations associated with the agreement are secured by a security interest in substantially all of its assets, other than its
	intellectual property.
	The Company borrowed the first tranche of $10.0 million upon the closing of the transaction on June 29, 2011 and borrowed the second tranche of $10.0 million in December 2011. The Company used a portion of the proceeds from the first tranche to repay the remaining obligations under that certain loan and security agreement between the Company and Pinnacle Ventures, L.L.C., or Pinnacle Ventures, dated September 16, 2008. The agreement with Pinnacle Ventures is described further below. The interest rate for each tranche was 8.50%. In connection with the loan, the Company issued Hercules seven-year warrants to purchase an aggregate of 274,508 shares of common stock at a price of $3.06 per share. See Note 7 “Warrants,” for
	further description.
	On December 16, 2013, AcelRx entered into an Amended and Restated Loan and Security Agreement, or the Loan Agreement with Hercules Technology II, L.P. and Hercules Technology Growth Capital, Inc., together, the Lenders, under which the Company may borrow up to $40.0 million in three tranches. The loans are represented by secured convertible term promissory notes, collectively, the Notes. The Loan Agreement amends and restates the Loan and Security Agreement between the Company and the Lenders dated as of June 29, 2011, or the Original Loan Agreement, as noted above. The Company borrowed the first tranche of $15.0 million upon closing of the transaction on December 16, 2013, and the second tranche of $10.0 million on June 16, 2014. The Company used approximately $8.6 million of the proceeds from the first tranche to repay its obligations under the Original Loan Agreement. The Company recorded the new debt at an estimated fair value of $24.9 million and $14.3 million as of December 31, 2014 and December 31, 2013, respectively.
	In accordance with ASC Topic No. 470, “Debt – Modifications and Extinguishments” (Topic No. 470), the amendment noted above was determined to be an extinguishment of the existing debt and an issuance of new debt. The Company reached this conclusion based on a comparison of discounted remaining cash flows of the original loan agreement compared to the amended loan agreement, the result of which was a greater than 10% difference in discounted cash flows. The Company determined this difference to be significant and recorded the new debt at estimated fair value.
	As a result of the extinguishment, the Company recorded a $1.2 million loss on extinguishment of debt which was recorded as interest income and other income (expense), net on the Statements of Comprehensive Loss during the year ended December 31, 2013. The loss on extinguishment was a non-cash write off, consisting of deferred debt charges, the unamortized portion of the original issue discount related to the Original Loan Agreement and other fees associated with extinguishing the debt, including the estimated fair value of warrants issued in connection with the amended loan agreement, facility and legal fees associated with the amended loan agreement and the value of the contingent put option liability associated with the original loan agreement at the time of the amendment.
	On September 24, 2014, the Company entered into an amendment, or the Amendment, to the Amended Loan Agreement with Hercules. The Amendment extends the time period under which the Company can draw down the third tranche, of up to $15.0 million, from March 15, 2015 to August 1, 2015, subject to the Company obtaining approval for Zalviso from the U.S. Food and Drug Administration. The Company does not believe it will receive FDA approval of Zalviso by August 1, 2015 and as such, will not have access to the third tranche under the current agreement.
	The interest rate for each tranche will be calculated at a rate equal to the greater of either (i) 9.10% plus the prime rate as reported from time to time in The Wall Street Journal minus 5.25%, and (ii) 9.10%. Payments under the Amended Loan Agreement are interest only until April 1, 2015 followed by equal monthly payments of principal and interest through the scheduled maturity date on October 1, 2017, or the Loan Maturity Date. In addition, a final payment equal to $1.7 million will be due on the Loan Maturity Date, or such earlier date specified in the Amended Loan Agreement. The Company’s obligations under the Amended Loan Agreement are secured by a security interest in substantially all of its assets, other than its intellectual property.
	If the Company prepays the Amended Loan Agreement prior to maturity, it will pay Hercules a prepayment charge, based on a percentage of the then outstanding principal balance, equal to 3% if the prepayment occurs prior to December 16, 2014, 2% if the prepayment occurs after December 16, 2014, but prior to December 16, 2015, or 1% if the prepayment occurs after December 16, 2015.
	Subject to certain conditions and limitations set forth in the Amended Loan Agreement, the Company has the right to convert up to $5.0 million of scheduled principal installments under the Notes into freely tradeable shares of the Company’s common stock, or Common Stock. The number of shares of Common Stock that would be issued upon conversion of the Amended Notes would be equal to the number determined by dividing (x) the product of (A) the principal amount to be paid in shares of Common Stock and (B) 103%, by (y) $9.30 (subject to certain proportional adjustments as provided for in the Amended Loan Agreement).
	The Amended Loan Agreement includes customary affirmative and restrictive covenants, but does not include any financial maintenance covenants, and also includes standard events of default, including payment defaults, breaches of covenants following any applicable cure period, a material impairment in the perfection or priority of Hercules’ security interest or in the value of the collateral, and events relating to bankruptcy or insolvency. Upon the occurrence of an event of default, a default interest rate of an additional 5% may be applied to the outstanding loan balances, and Hercules may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Amended Loan Agreement.
	In connection with the Amended Loan Agreement, the Company issued a warrant to each Lender which, collectively, are exercisable for an aggregate of 176,730 shares of common stock and each carry an exercise price of $6.79 per share. See Note 7 “Warrants,” for further description.
	Upon an event of default, including a change of control, Hercules has the option to accelerate repayment of the Amended Loan Agreement, including payment of any applicable prepayment charges, which range from 1%-3% of the outstanding loan balance and accrued interest, as well as a final payment fee of $1.7 million. This option is considered a contingent put option liability, as the holder of the loan may exercise the option in the event of default, and is considered an embedded derivative, which must be valued and separately accounted for in the Company’s financial statements. As the amendment of the loan agreement was considered an extinguishment, the contingent put option liability associated with the Original Loan Agreement, which had an estimated fair value of $32,000 at the time of the amendment, was written off as a part of the loss on extinguishment, and a new contingent put option liability was established. As of December 31, 2014 and December 31, 2013, the estimated fair value of the contingent put option liability was $282,000 and $334,000, respectively, which was determined by using a risk-neutral valuation model, wherein the fair value of the underlying debt facility is estimated both with and without the presence of the default provisions, holding all other assumptions constant. The resulting difference between the two estimated fair values is the estimated fair value of the default provisions, or the contingent put option. The fair value of the underlying debt facility is estimated by calculating the expected cash flows in consideration of an estimated probability of default and expected recovery rate in default, and discounting such cash flows back to the reporting date using a risk-free rate. The contingent put option liability was recorded as a debt discount to the loan and consequently a reduction to the carrying value of the loan. The contingent put option liability is revalued at the end of each reporting period and any change in the fair value is recognized in interest income and other income (expense), net in the Statements of Comprehensive Loss.
	As of December 31, 2014, the Company had outstanding borrowings under the Amended Loan Agreement of $25.0 million. Interest expense related to the Amended Loan Agreement was $2.6 million for the year ended December 31, 2014, $0.5 million of which represented amortization of the debt discount.
	As of December 31, 2013, the Company had outstanding borrowings under the Amended Loan Agreement of $15.0 million. Amortization of the debt discount prior to amending the Hercules loan and security agreement in December 2013, which was recorded as interest expense, was $0.4 million for the year ended December 31, 2013.
	As of December 31, 2012, the Company had outstanding borrowings under the Hercules loan and security agreement of $16.0 million, net of debt discount of $0.5 million. Amortization of the debt discount, which was recorded as interest expense, was $0.5 million for the year ended December 31, 2012.
	Future Payments on Long-Term Debt
	The following table summarizes our outstanding future payments associated with the Company’s long-term debt as of December 31, 2014 (in thousands):
	2015	$	8,982
	2016		11,218
	2017		10,176
	Total minimum payments		30,376
	Less amount representing interest		(3,676	)
	Notes payable, gross		26,700
	Balloon payment		(1,700	)
	Unamortized discount on notes payable		(95	)
			24,905
	Less current portion of notes payable, including unamortized discount		6,859
	Notes payable, less current portion	$	18,046

Note_7_Warrants

Note 7 - Warrants	12 Months Ended
	Dec. 31, 2014
Warrants Disclosure [Abstract]
Warrants Disclosure [Text Block]	7. Warrants
	Series A Warrants
	As of December 31, 2014, warrants to purchase 3,425 shares of common stock had not been exercised and were still outstanding. These warrants expire in March 2017.
	PinnacleWarrants
	In February 2013, warrants to purchase 228,264 shares were net exercised, for 58,580 shares of common stock. As of December 31, 2014, no warrants to purchase shares of common stock issued to Pinnacle were outstanding.
	Hercules Warrants
	In connection with the Amended Loan Agreement, executed in December 2013, the Company issued warrants to Hercules which are exercisable for an aggregate of 176,730 shares of common stock with an exercise price of $6.79 per share (the “Warrants”). Each Warrant may be exercised on a cashless basis. The Warrants are exercisable for a term beginning on the date of issuance and ending on the earlier to occur of five years from the date of issuance or the consummation of certain acquisitions of the Company as set forth in the Warrants. The number of shares for which the Warrants are exercisable and the associated exercise price are subject to certain proportional adjustments as set forth in the Warrants. The Company estimated the fair value of these warrants as of the issuance date to be $1.1 million, which was used in the estimating the fair value of the amended debt instrument and was recorded as equity. The fair value of the warrants was calculated using the Black-Scholes option-valuation model, and was based on the strike price of $6.79, the stock price at issuance of $9.67, the five-year contractual term of the warrants, a risk-free interest rate of 1.55%, expected volatility of 71% and 0% expected dividend yield.
	As of December 31, 2014, warrants to purchase 176,730 shares of common stock issued to Hercules had not been exercised and were still outstanding. These warrants expire in December 2018.
	In connection with the original loan and security agreement with Hercules, executed in June 2011, the Company issued to Hercules warrants to purchase an aggregate of 274,508 shares of common stock at a price of $3.06 per share. The warrants may be exercised on a cashless basis. The warrants are exercisable for a term beginning on the date of issuance and ending on the earlier to occur of seven years from the date of issuance or the consummation of certain acquisitions of the Company as set forth in the warrants. During June and July 2013, warrants to purchase 274,508 shares were net exercised, for 183,404 shares of common stock.
	2012 Private Placement Warrants
	In connection with the Private Placement, completed in June 2012, the Company issued PIPE warrants to purchase up to 2,630,103 shares of common stock. The per share exercise price of the PIPE warrants was $3.40 which equals the closing consolidated bid price of the Company’s common stock on May 29, 2012, the effective date of the Purchase Agreement. The PIPE warrants issued in the Private Placement became exercisable six months after the issuance date, and expire on the five year anniversary of the initial exercisability date. Under the terms of the PIPE warrants, upon certain transactions, including a merger, tender offer, sale of all or substantially all of the assets of the Company or if a person or group shall become the owner of 50% of the Company’s issued and outstanding common stock, which is outside of the Company’s control, each PIPE warrant holder may elect to receive a cash payment in exchange for the warrant, in an amount determined by application of the Black-Scholes option-pricing model. Accordingly, the PIPE warrants were recorded as a liability at fair value, as determined by the Black-Scholes option-pricing model, and then marked to fair value each reporting period, with changes in estimated fair value recorded through the Statements of Comprehensive Loss in interest income and other income (expense), net. The Black-Scholes assumptions used to value the PIPE warrants are disclosed in Note 2 “Investments and Fair Value Measurement.”
	Upon execution of the Purchase Agreement, the fair value of the PIPE warrants was estimated to be $5.8 million, which was recorded as a liability. As of December 31, 2014, the fair value of the PIPE warrants was estimated to be $5.6 million. The change in fair value for the year ended December 31, 2014, which was recorded as other income, was $7.0 million. The change in fair value for the year ended December 31, 2013, which was recorded as other expense, was $14.1 million.
	During the year ended December 31, 2014, PIPE warrants to purchase 135,000 shares were net exercised for 91,488 shares of common stock. During the year ended December 31, 2013, warrants to purchase 1,135,589 shares were net exercised, for 808,078 shares of common stock. As of December 31, 2014, PIPE warrants to purchase 1,359,514 shares of common stock issued in connection with the Private Placement had not been exercised and were outstanding. These warrants expire in November 2017.

Note_8_Commitments_and_Conting

Note 8 - Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	8. Commitments and Contingencies
	Operating Leases
	In December 2011, the Company entered into a non-cancelable lease agreement for approximately 13,787 square feet of office and laboratory facilities in Redwood City, California, which serve as the Company headquarters, effective April 2012. The lease agreement expires in May 2016. Rent expense from the facility lease is recognized on a straight-line basis from the inception of the lease in December 2011, the early access date, through the end of the lease.
	Prior to April 2012, the Company was subject to a non-cancelable lease agreement for approximately 11,305 square feet of office and laboratory facilities in Redwood City, California, which served as the Company headquarters for the duration of the lease term. The lease term commenced in April 2007 and expired in April 2012. Rent expense from the facility lease was recognized on a straight-line basis from the inception of the lease in January 2007, the early access date, through the end of the lease.
	In May 2014, the Company entered into an amendment, or the Lease Amendment, to that certain lease dated December 21, 2011, with Metropolitan Life Insurance Company, or the Existing Lease, for 13,787 square feet of space located at 301 Galveston Drive, Redwood City, California, or the Current Premises. Pursuant to the Lease Amendment, the term of the Existing Lease has been extended for a period of twenty (20) months and twenty-two (22) days and expiring January 31, 2018, or the Expiration Date, unless sooner terminated pursuant to the terms of the Existing Lease. In addition, the Lease Amendment included a new lease on an additional 12,106 square feet of office space, or the Expansion Space, which is adjacent to the current premises. The new lease for the Expansion Space has a term of 42 months commencing on August 1, 2014, and expiring on the Expiration Date. The Company has an option to extend the term of the Lease Amendment for an additional five years, which would commence upon the Expiration Date, at a market rate determined according to the Existing Lease.
	Rent expense was $0.5 million, $0.3 million and $0.3 million during the years ended December 31, 2014, 2013 and 2012, respectively.
	Future minimum payments under the lease agreement as of December 31, 2014 are as follows (in thousands):
	Year Ending December 31:
	2015	$	683
	2016		717
	2017		737
	2018		62
	Total minimum payments	$	2,199
	In addition, the Company will pay the Landlord specified percentages of certain operating expenses and taxes related to the leased facility incurred by the Landlord.
	Litigation
	On October 1, 2014, a securities class action complaint was filed in the U.S. District Court for the Northern District of California against AcelRx and certain of the Company’s current and former officers. The complaint alleges that between December 2, 2013 and September 25, 2014, AcelRx and certain of the Company’s officers violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 in connection with statements related to the Company’s lead drug candidate, Zalviso. The complaint seeks unspecified damages, interest, attorneys’ fees, and other costs. On December 1, 2014, three purported shareholders filed motions to appoint lead plaintiff and to appoint lead counsel. On February 24, 2015, the court issued an order appointing the lead plaintiff and lead counsel in the matter. Lead Plaintiff has until April 10, 2015 to file an amended complaint. The last day for the Company to respond to the amended complaint is May 26, 2015. The Company believes that it has meritorious defenses and intends to defend against this lawsuit vigorously.
	From time to time the Company may be involved in additional legal proceedings arising in the ordinary course of business. The Company does not have contingent liabilities established for any litigation matters.
	Manufacturing Agreements
	Patheon
	In January 2013, the Company and Patheon entered into a Manufacturing Services Agreement, or the Services Agreement, and a related Amended and Restated Capital Expenditure and Equipment Agreement, or the Amended Capital Agreement, relating to the manufacture of sufentanil sublingual tablets, or the Product, for use with the Company’s Zalviso System.
	Under the terms of the Services Agreement, the Company has agreed to purchase, subject to Patheon’s continued material compliance with the terms of the Services Agreement, all of its Product requirements for the United States, Canada and Mexico from Patheon during the Initial Term of the Services Agreement (as defined below), and at least eighty percent (80%) of its Product requirements for such territories after the Initial Term.
	The term of the Services Agreement extends until December 31, 2017, or the Initial Term, and will automatically renew thereafter for periods of two years, unless terminated by either party upon eighteen months’ prior written notice; provided, however, that the Services Agreement may not be terminated without cause prior to the end of the Initial Term.
	Under the terms of the Amended Capital Agreement, the Company has made and has the option to make certain future modifications to Patheon’s Cincinnati facility and which would be the responsibility of the Company. If additional equipment and facility modifications are required to meet the Company’s Product needs, the Company may be required to contribute to the cost of such additional equipment and facility modifications. The Amended Capital Agreement also requires that the Company make payments in 2012 and 2013 totaling $480,000, which the Company made, to Patheon to partially offset taxes incurred and paid by Patheon in connection with facility modifications already completed by Patheon. There were no such payments due in 2014. The Company can seek reimbursement from Patheon for these payments if it receives approval from the FDA for Zalviso. The Amended Capital Agreement further requires that the Company pay a maximum “overhead fee” of $200,000 annually during the term of the Services Agreement, which amount may be reduced to $0 based on the amount of annual revenues earned by Patheon under the Services Agreement and the pre-existing development agreements. No fee was due in 2013 or 2014 based on the amount of revenues earned by Patheon from the Company.
	Expenditures associated with the aforementioned agreements are primarily driven by the potential commercial requirements and demand for the Company’s products, none of which have been approved for commercialization; accordingly, the amounts and timing of such future expenditures cannot be determined at this time.
	Grünenthal
	On December 16, 2013, the Company and Grünenthal GmbH, or Grünenthal, entered into a Collaboration and License Agreement, or the License Agreement, and related Manufacture and Supply Agreement, or the Manufacturing Agreement, and together with the License Agreement, the Agreements. The License Agreement grants Grünenthal rights to commercialize Zalviso, the Company’s novel sublingual patient-controlled analgesia, or PCA, system, or the Product, in the countries of the European Union, Switzerland, Liechtenstein, Iceland, Norway and Australia, or the Territory, for human use in pain treatment within or dispensed by hospitals hospices, nursing homes and other medically-supervised settings, or the Field.
	Under the terms of the Manufacturing Agreement, the Company will manufacture and supply the Product for use in the Field for the Territory exclusively for Grünenthal. Grünenthal shall purchase from AcelRx, during the first five years after the effective date of the Manufacturing Agreement, 100% and thereafter 80% of Grünenthal’s and its sublicensees’ and distributors’ requirements of Product for use in the Field for the Territory. The Product will be supplied at the Company’s fully burdened manufacturing cost (as defined in the Manufacturing Agreement). The Manufacturing Agreement requires the Company to use commercially reasonable efforts to enter stand-by contracts with third parties providing significant supply and manufacturing services and under certain specified conditions permits Grünenthal to use a third party back-up manufacturer to manufacture the Product for Grünenthal’s commercial sale in the Territory.
	Unless earlier terminated, the Manufacturing Agreement continues in effect until the later of the expiration of the obligation of Grünenthal to make royalty and supply and trademark fee payments or the end of any transition period for manufacturing obligations due to the expiration or termination of the License Agreement. The Manufacturing Agreement is subject to earlier termination in connection with certain termination events in the License Agreement, in the event the parties mutually agree, by a party in the event of an uncured material breach by the other party or upon the bankruptcy or insolvency of either party.
	Under the Supply Agreement, the Company will exclusively manufacture and supply the Product to Grünenthal for the Field in the Territory.
	Expenditures associated with the aforementioned agreements are primarily driven by the potential commercial requirements and demand for the Company’s products, none of which are currently approved for commercial use; accordingly, the amounts and timing of such future expenditures cannot be determined at this time.

Note_9_Stockholders_Equity

Note 9 - Stockholders' Equity	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	9. Stockholders’ Equity
	Common Stock
	Public Offerings
	On May 19, 2014, the Company filed with the Securities and Exchange Commission, or SEC, a shelf Registration Statement on Form S-3, as amended on Form S-3/A on July 6, 2014. The shelf Registration Statement (File Number 333-196089) was declared effective by the SEC on July 12, 2014, providing the Company with the ability to offer and sell up to an aggregate of $150 million of common stock from time to time in one or more offerings. The terms of any such future offering would be established at the time of such offering.
	On July 23, 2013, AcelRx completed an underwritten public offering of 4,370,000 shares of common stock, at a price of $11.65 per share to the public. The total gross proceeds of this offering were $50.9 million with net proceeds to AcelRx of $47.9 million after deducting underwriting discounts and commissions and other expenses payable by AcelRx.
	In December 2012, AcelRx completed an underwritten public offering, in which the Company sold an aggregate of 14,375,000 shares of its common stock at a public offering price of $3.31 per share, resulting in net proceeds of $44.1 million, after deducting underwriting discounts and commissions and other offering related expenses totaling $3.5 million.
	Private Placement Offering
	On June 1, 2012, or the Issuance Date, the Company issued an aggregate of 2,922,337 shares of common stock and warrants to purchase up to 2,630,103 shares of common stock, or the PIPE warrants, for aggregate gross proceeds of $10.0 million, or the Private Placement. Costs related to the offering were $0.9 million. The shares of common stock and PIPE warrants issued in the Private Placement were sold pursuant to a Securities Purchase Agreement, or Purchase Agreement, dated May 29, 2012, between the Company and certain purchasers, including certain entities affiliated with Mark Wan and Stephen J. Hoffman, members of the Company’s board of directors. Pursuant to the Purchase Agreement, AcelRx sold shares of common stock and PIPE warrants to purchase common stock in immediately separable “Units,” with each Unit consisting of (i) one share of common stock and (ii) a PIPE warrant to purchase 0.9 of a share of common stock. The per share exercise price of the PIPE warrants was $3.40. The offering price per Unit was $3.40 for non-affiliated investors, and $3.5125 for affiliated investors, which equals the sum of (i) $3.40, the closing consolidated bid price of the Company’s common stock on May 29, 2012, plus (ii) $0.1125 (which is equal to $0.125 per PIPE warrant share, multiplied by 0.9), for an aggregate amount of $10.0 million. The PIPE warrants issued in the Private Placement became exercisable six months after the Issuance Date, and expire on the five year anniversary of the initial exercisability date.
	In connection with the Private Placement, the Company filed a registration statement with the U.S. Securities and Exchange Commission, or SEC, registering for resale the shares of common stock and shares of common stock issuable upon exercise of the warrants sold in the Private Placement. The registration statement was declared effective by the SEC in July 2012.
	Stock Plans
	2011 Equity Incentive Plan
	In January 2011, the board of directors adopted, and the Company’s stockholders approved, the 2011 Equity Incentive Plan, or 2011 Incentive Plan, as a successor to the 2006 Plan. The 2011 Incentive Plan became effective immediately upon the execution and delivery of the underwriting agreement for the IPO on February 10, 2011. As of February 10, 2011, no more awards may be granted under the 2006 Plan, although all outstanding stock options and other stock awards previously granted under the 2006 Plan will continue to remain subject to the terms of the 2006 Plan. The 51,693 shares reserved under the 2006 Plan that remained available for future grant at the time of the IPO were transferred to the share reserve of the 2011 Incentive Plan.
	The initial aggregate number of shares of the Company’s common stock that may be issued pursuant to stock awards under the 2011 Incentive Plan is 1,875,000 shares, which number was the sum of (i) 51,693 shares remaining available for future grant under the 2006 Plan at the time of the execution and delivery of the underwriting agreement for the Company’s IPO, and (ii) an additional 1,823,307 new shares. Then, the number of shares of common stock reserved for issuance under the 2011 Incentive Plan will automatically increase on January 1st each year, starting on January 1, 2012 and continuing through January 1, 2020, by 4% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or such lesser number of shares of common stock as determined by the board of directors.
	On March 17, 2014, the Company filed a Form S-8 (File Number 333-194634) with the SEC registering 1,722,023 shares of common stock, par value $0.001 per share, under the 2011 Equity Incentive Plan.
	On March 12, 2013, the Company filed a Form S-8 (File Number 333-187206) with the SEC registering 1,482,201 shares of common stock, par value $0.001 per share, under the 2011 Equity Incentive Plan.
	On March 26, 2012, the Company filed a Form S-8 (File Number 333-180334) with the SEC registering 782,711 shares of common stock, par value $0.001 per share, under the 2011 Equity Incentive Plan.
	2011 Employee Stock Purchase Plan
	Additionally, in January 2011, the board of directors adopted, and the Company’s stockholders approved, the 2011 Employee Stock Purchase Plan, or the ESPP, which also became effective immediately upon the execution and delivery of the underwriting agreement for the IPO.
	Initially, 250,000 shares of the Company’s common stock were authorized for issuance under the ESPP pursuant to purchase rights granted to the Company’s employees or to employees of any of its designated affiliates. The number of shares of the Company’s common stock reserved for issuance will automatically increase on January 1st each year, starting January 1, 2012 and continuing through January 1, 2020, in an amount equal to the lower of (1) 2% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or (2) a number of shares of common stock as determined by the board of directors. If a purchase right granted under the ESPP terminates without having been exercised, the shares of the Company’s common stock not purchased under such purchase right will be available for issuance under the ESPP.
	On March 26, 2012, the Company filed a Form S-8 (File Number 333-180334) with the SEC registering 391,355 shares of common stock, par value $0.001 per share, under the 2011 Employee Stock Purchase Plan.
	As of December 31, 2014, 254,337 shares have been issued to employees and there are 387,018 shares available for issuance under the ESPP. The weighted average fair value of shares issued under the ESPP in 2014, 2013 and 2012 was $4.35, $3.97 and $2.45 per share, respectively.
	2006 Stock Plan
	In August 2006, the Company established the 2006 Plan in which 342,000 shares of common stock were originally reserved for the issuance of incentive stock options, or ISOs, and nonstatutory stock options, or NSOs, to employees, directors or consultants of the Company. In February 2008, an additional 375,000 shares of common stock were reserved for issuance under the 2006 Plan and, in November 2009, an additional 1,376,059 shares of common stock were reserved for issuance under the 2006 Plan. Per the 2006 Plan, the exercise price of ISOs and NSOs granted to a stockholder who at the time of grant owns stock representing more than 10% of the voting power of all classes of the stock of the Company could not be less than 110% of the fair value per share of the underlying common stock on the date of grant. Effective upon the execution and delivery of the underwriting agreement for the Company’s IPO, no additional stock options or other stock awards may be granted under the 2006 Plan.

Note_10_Stockbased_Compensatio

Note 10 - Stock-based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	10. Stock-Based Compensation
	The Company recorded total stock-based compensation expense for stock options, stock awards and the ESPP as follows (in thousands):
			Year Ended December 31,
			2014				2013				2012
	Research and development		$	2,252			$	1,657			$	998
	General and administrative			2,188				1,822				1,152
	Total		$	4,440			$	3,479			$	2,150
	The following table summarizes option activity under the 2011 Plan and 2006 Plan:
			Number				Weighted-				Weighted-			Aggregate
			of Stock Options				Average				Average			Intrinsic
			Outstanding				Exercise				Remaining			Value
							Price				Contractual
											Life (Years)
														(in thousands)
	31-Dec-11			2,395,968			$	3.08
	Granted			1,213,391				3.36
	Forfeited			(165,781	)			3.23
	Exercised			(43,767	)			2.32
	31-Dec-12			3,399,811			$	3.18
	Granted			1,958,727				5.99
	Forfeited			(17,917	)			8.82
	Exercised			(431,216	)			3.03
	31-Dec-13			4,909,405			$	4.29
	Granted			2,512,500				8.74
	Forfeited			(615,854	)			7.76
	Exercised			(439,288	)			3.9
	31-Dec-14			6,366,763			$	5.74				8.1		$	11,106
	Vested and exercisable options—December 31, 2014			2,920,611			$	3.79				7		$	8,856
	Vested and expected to vest—December 31, 2014			6,128,922			$	5.67				8.1		$	11,006
	As of December 31, 2014, there were 98,366 shares available for future grant under the 2011 Plan. In January 2015, an additional 1,748,495 shares were authorized for issuance under the 2011 Incentive Plan.
	Additional information regarding the Company’s stock options outstanding and vested and exercisable as of December 31, 2014 is summarized below:
								Options Outstanding										Options Vested and Exercisable
		Exercise Prices						Number of				Weighted-Average			Weighted-Average			Shares Subject		Weighted-Average
								Stock Options				Remaining			Exercise Price per			to Stock		Exercise Price per
								Outstanding				Contractual Life			Share			Options		Share
												(Years)
		$	1.2	-	$2.56				995,304				7.3		$	2.39			995,303	$	2.39
		$	3.11	-	$5.31				2,850,209				7.4		$	4.44			1,745,726	$	4.2
		$	5.45	-	$8.18				1,190,000				9.4		$	6.52			110,207	$	5.64
		$	10.22	-	$11.71				1,331,250				9.3		$	10.32			69,375	$	10.46
									6,366,763				8.1		$	5.74			2,920,611	$	3.79
	The weighted average grant-date fair value of options granted during the years ended December 31, 2014, 2013 and 2012 was $5.57, $4.15 and $2.25 per share, respectively. As of December 31, 2014, total stock-based compensation expense related to unvested options to be recognized in future periods was $13.3 million which is expected to be recognized over a weighted-average period of 3.0 years. The grant date fair value of shares vested during the years ended December 31, 2014, 2013 and 2012 was $3.2 million, $1.9 million and $1.3 million, respectively. The total intrinsic value of options exercised during the years ended December 31, 2014, 2013 and 2012 was $2.3 million, $3.6 million and $85,000, respectively.
	The Company used the following assumptions to calculate the fair value of each employee stock option:
			Year Ended December 31,
			2014						2013					2012
	Expected term (in years)			5.25	-	6.25				5.75	-	6.25			5.75	-	6.25
	Risk-free interest rate			1.76%	-	1.92%				1.02%	-	2.96%			0.60%	-	1.74%
	Expected volatility			69	-	72%				80%					80%
	Expected dividend rate			0%						0%					0%
	Restricted Stock Units
	In March 2011, the Company granted 343,815 Restricted Stock Units, or RSUs, to employees and directors under the 2011 Plan at a grant date fair value of $3.45. The fair value of the RSUs was determined on the date of grant based on the market price of the Company’s common stock. RSUs are recognized as expense ratably over the vesting period and the Company’s RSU’s generally vest over three years as follows: 25% on the 6 month anniversary of the vesting commencement date, 25% on the 12 month anniversary of the vesting commencement date, 25% on the 24 month anniversary of the vesting commencement date and 25% on the 36 month anniversary of the vesting commencement date, so long as the RSU recipient continues to provide services to the Company. As of December 31, 2014, there were no RSUs outstanding. The expense related to RSUs during the years ended December 31, 2014, 2013 and 2012 was $56,000, $290,000 and $315,000, respectively.
	A summary of restricted stock unit award activity under the 2011 Plan is as follows:
			Number of				Weighted
			Restricted				Average
			Stock Units				Grant Date
							Fair Value
	Restricted stock units outstanding December 31, 2012			161,096			$	3.45
	Granted			—				—
	Vested			(95,331	)			(3.45	)
	Forfeited			—				—
	Restricted stock units outstanding, December 31, 2013			65,765			$	3.45
	Granted			—				—
	Vested			(65,765	)			(3.45	)
	Forfeited			—				—
Restricted stock units outstanding, December 31, 2014			—			$	—

Note_11_Net_Loss_Per_Share_of_

Note 11 - Net Loss Per Share of Common Stock	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	11. Net Loss per Share of Common Stock
	The Company’s basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. The diluted net loss per share of common stock is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, options to purchase common stock and warrants to purchase common stock were considered to be common stock equivalents. In periods with a reported net loss, common stock equivalents are excluded from the calculation of diluted net loss per share of common stock if their effect is antidilutive.
	During the year ended December 31, 2014, the PIPE warrants had a dilutive impact to net loss per share due to a lower share price at December 31, 2014, compared to the closing share price on December 31, 2013. The decrease in share price created a lower Black-Scholes value and lower liability for the PIPE warrants, which resulted in other income during the year ended December 31, 2014. The calculation of diluted net loss per share requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the PIPE warrants and the presumed exercise of such securities are dilutive to loss per share for the period, adjustments to net loss used in the calculation are required to remove the change in fair value of the PIPE warrants for the period. Likewise, adjustments to the denominator are required to reflect the related dilutive shares.
	The following table is a reconciliation of the numerators and denominators used in the calculation of basic and diluted net loss per share computations for the years ended December 31, 2014, 2013 and 2012:
		Years Ended December 31,
		2014			2013			2012
		(in thousands, except share and per share amounts)
	Numerator:
	Net loss used to compute net loss per share
	Basic	$	(33,353	)	$	(23,426	)	$	(33,363	)
	Adjustments for change in fair value of warrant liability		(6,988	)		—			—
	Diluted	$	(40,341	)	$	(23,426	)	$	(33,363	)
	Denominator:
	Weighted average shares outstanding used to compute net loss per share:
	Basic		43,427,111			39,746,678			22,124,637
	Dilutive effect of warrants		895,186			—			—
	Diluted		44,322,297			39,746,678			22,124,637
	Net loss per share—basic	$	(0.77	)	$	(0.59	)	$	(1.51	)
	Net loss per share—diluted	$	(0.91	)	$	(0.59	)	$	(1.51	)
	The following outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share of common stock for the periods presented because including them would have been antidilutive:
		Year Ended December 31,
		2014			2013			2012
	Stock options to purchase common stock		6,366,763			4,909,405			3,399,811
	Restricted Stock Units		—			65,765			161,096
	Common stock warrants		180,155			1,674,669			3,136,300

Note_12_Accounts_Payable_and_A

Note 12 - Accounts Payable and Accrued Liabilities	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
Accounts Payable and Accrued Liabilities Disclosure [Text Block]	12. Accounts Payable and Accrued Liabilities
	Accounts payable and accrued liabilities consist of the following (in thousands):
		December 31,
		2014		2013
	Accounts payable	$	2,249	$	2,341
	Accounts payable associated with property and equipment		182		—
	Accrued compensation and employee benefits		2,540		2,397
	Accrued research and development expenses		124		248
	Accrued liabilities associated with property and equipment		23		725
	Accrued liabilities associated with Grünenthal collaboration		499		—
	Professional fees		139		230
	Interest payable		196		61
	Other		133		243
	Total accounts payable and accrued liabilities	$	6,085	$	6,245

Note_13_401k_Plan

Note 13 - 401(k) Plan	12 Months Ended
	Dec. 31, 2014
Benefit Plans [Abstract]
Benefit Plans [Text Block]	13. 401(k) Plan
	The Company sponsors a 401(k) plan that stipulates that eligible employees can elect to contribute to the 401(k) plan, subject to certain limitations. Pursuant to the 401(k) plan, the Company makes a discretionary safe harbor contribution equal to 3% of the related compensation. Eligible employees are 100% vested in this safe harbor contribution regardless of whether they make salary deferrals into the 401(k) plan. Company contributions were $201,000, $143,000 and $120,000 for the years ended December 31, 2014, 2013 and 2012, respectively.

Note_14_Income_Taxes

Note 14 - Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	14. Income Taxes
	The Company did not record a provision for income taxes during the years ended December 31, 2014, 2013 and 2012. Net deferred tax assets as of December 31, 2014 and 2013 consist of the following (in thousands):
		December 31,			December 31,
		2014			2013
	Deferred tax assets:
	Accruals and other	$	4,446		$	2,172
	Research credits		4,413			3,553
	Net operating loss carryforward		42,330			36,279
	Section 59(e) R&D expenditures		17,083			10,339
	Total deferred tax assets		68,272			52,343
	Valuation allowance	$	(68,272	)	$	(52,343	)
	Net deferred tax assets	$	—		$	—
	Reconciliations of the statutory federal income tax to the Company’s effective tax during the years ended December 31, 2014, 2013 and 2012 are as follows (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Tax at statutory federal rate	$	(11,392	)	$	(7,965	)	$	(11,343	)
	State tax—net of federal benefit		(2,501	)		(716	)		(1,953	)
	PIPE Warrant liability		(2,393	)		4,898			540
	General Business credits		(628	)		(1,326	)		—
	Stock Options		543			—			—
	Other		20			(80	)		807
	Change in valuation allowance		16,351			5,189			11,949
	Provision (benefit) for income taxes	$	—		$	—		$	—
	ASC 740 requires that the tax benefit of net operating losses, temporary differences and credit carryforwards be recorded as an asset to the extent that management assesses that realization is “more likely than not.” Realization of deferred tax assets is dependent on future taxable income, if any, the timing and the amount of which are uncertain. Accordingly, the deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $16.4 million, $4.8 million and $11.9 million during the years ended December 31, 2014, 2013 and 2012, respectively. The amount of the valuation allowance for deferred tax assets associated with excess tax deduction from stock based compensation arrangement that is allocated to contributed capital if the future tax benefits are subsequently recognized is $2.8 million.
	As of December 31, 2014, the Company had federal net operating loss carryforwards of $109.1 million, which begin to expire in 2025. As of December 31, 2014, the Company had state net operating loss carryforwards of $109.1 million, which begin to expire in 2015.
	As of December 31, 2014, the Company had federal research credit carryovers of $3.3 million, which begin to expire in 2026. As of December 31, 2014, the Company had state research credit carryovers of $1.7 million, which will carryforward indefinitely.
	Under Section 382 of the Internal Revenue Code of 1986, as amended, if a corporation undergoes an “ownership change”, generally defined as a greater than 50% change (by value) in its equity ownership over a three year period, the corporation’s ability to use its pre-change net operating loss carryforwards and other pre-change tax attributes, such as research credits, to offset its post-change income may be limited. Based on an analysis performed by the Company as of December 31, 2014, it was determined that two ownership changes have occurred since inception of the Company. The first ownership change occurred in 2006 at the time of the Series A financing and, as a result of the change, $1.4 million in federal and state net operating loss carryforwards will expire unutilized. In addition, $26,000 in federal and state research and development credits will expire unutilized. The second ownership change occurred in July 2013 at the time of the underwritten public offering; however, the Company believes the resulting annual imposed limitation on use of pre-change tax attributes is sufficiently high that the limit itself will not result in unutilized pre-change tax attributes.
	Uncertain Tax Positions
	A reconciliation of the beginning and ending balances of the unrecognized tax benefits during the years ended December 31, 2014, 2013 and 2012 is as follows (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Unrecognized benefit—beginning of period	$	1,341		$	810		$	748
	Gross decreases—prior period tax positions		—			221			(17	)
	Gross increases—current period tax positions		326			310			79
	Unrecognized benefit—end of period	$	1,667		$	1,341		$	810
	The entire amount of the unrecognized tax benefits would not impact the Company’s effective tax rate if recognized.
	Accrued interest and penalties related to unrecognized tax benefits are classified as income tax expense and were immaterial. The Company files income tax returns in the United States and in California. The tax years 2007 through 2013 remain open in both jurisdictions. The Company is not currently under examination by income tax authorities in federal, state or other foreign jurisdictions.

Note_15_Subsequent_Events

Note 15 - Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events [Text Block]	15. Subsequent Events
	In March 2015, the Company announced that it had received correspondence from the FDA stating that in addition to the bench testing and two Human Factors studies the Company had performed for Zalviso in order to address the issues raised in the CRL, an additional clinical study is needed to assess the risk of inadvertent dispensing and overall risk of dispensing failures. The Company intends to meet with the FDA to discuss and clarify the need for an additional clinical study, and the potential design and objectives of such a study. This event has no impact on the Financial Statements as presented herein.

Note_16_Unaudited_Quarterly_Fi

Note 16 - Unaudited Quarterly Financial Data	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	16. Unaudited Quarterly Financial Data (in thousands, except per share amounts)
	The following table sets forth certain unaudited quarterly financial data for the eight quarters ended December 31, 2014. The unaudited information set forth below has been prepared on the same basis as the audited information and includes all adjustments necessary to present fairly the information set forth herein. The operating results for any quarter are not indicative of results for any future period. All data is in thousands except per share data.
		2014												2013
		Q1			Q2			Q3			Q4			Q1			Q2			Q3			Q4
	Revenues	$	95		$	71		$	4,825		$	226		$	940		$	407		$	548		$	27,607
	Operating Expenses	$	8,636		$	12,331		$	9,894		$	12,005		$	11,509		$	8,178		$	8,858		$	7,624
	Net income / (loss)	$	(9,631	)	$	(10,575	)	$	671		$	(13,818	)	$	(12,762	)	$	(17,447	)	$	(10,986	)	$	17,769
	Net income / (loss) per share (basic)	$	(0.22	)	$	(0.24	)	$	0.02		$	(0.32	)	$	(0.34	)	$	(0.47	)	$	(0.26	)	$	0.41
	Net income / (loss) per share (diluted)	$	(0.22	)	$	(0.30	)	$	(0.13	)	$	(0.32	)	$	(0.34	)	$	(0.47	)	$	(0.26	)	$	0.39

Accounting_Policies_by_Policy_

Accounting Policies, by Policy (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
The Company [Policy Text Block]	The Company
	AcelRx Pharmaceuticals, Inc., or the Company or AcelRx, was incorporated in Delaware on July 13, 2005 as SuRx, Inc., and in January 2006, the Company changed its name to AcelRx Pharmaceuticals, Inc. The Company’s operations are based in Redwood City, California.
	AcelRx is a specialty pharmaceutical company focused on the development and commercialization of innovative therapies for the treatment of acute pain. AcelRx intends to commercialize its product candidates in the United States and license the development and commercialization rights to its product candidates for sale outside of the United States through strategic partnerships and collaborations. On July 25, 2014, the U.S. Food and Drug Administration, or FDA, issued a Complete Response Letter, or CRL, for the Company’s new drug application, or NDA, for Zalviso™ (sufentanil sublingual tablet system), formerly known as ARX-01. In March 2015, the Company announced the receipt of correspondence from the FDA stating that in addition to the bench testing and two Human Factors studies it has performed, an additional clinical study is needed to assess the risk of inadvertent dispensing and overall risk of dispensing failures. The proposed indication for Zalviso is for the management of moderate-to-severe acute pain in adult patients in the hospital setting. Zalviso consists of sufentanil sublingual tablets delivered by the Zalviso System, a needle-free, handheld, patient-administered, pain management system (together, “Zalviso”).
	The Company has incurred recurring operating losses and negative cash flows from operating activities since inception and expects to continue to incur negative cash flows until its product candidates are approved for marketing in the United States and other countries, in which it has and intends to license its products, which may never occur. In previous years, prior to the completion of the clinical development program for Zalviso and the commercial collaboration of Zalviso, AcelRx was considered a development stage company.
	The Company has one business activity, which is the development and commercialization of product candidates for the treatment of pain, and a single reporting and operating unit structure.
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation
	The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and the accompanying notes. Actual results could differ from those estimates.
Use of Estimates, Policy [Policy Text Block]	Use of Estimates
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Management evaluates its estimates on an ongoing basis including critical accounting policies. Estimates are based on historical experience and on various other market-specific and other relevant assumptions that the Company believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates.
Concentration Risk, Credit Risk, Policy [Policy Text Block]	Concentration of Risk
	The Company invests cash that is currently not being used for operational purposes in accordance with its investment policy in debt securities of the U.S. Treasury and U.S. government sponsored agencies and overnight deposits. The Company is exposed to credit risk in the event of default by the institutions holding the cash equivalents and available-for-sale securities to the extent recorded on the balance sheet. Our cash and cash equivalent balances can be in excess of federally
	insured amounts.
Cash, Cash Equivalents, and Marketable Securities [Policy Text Block]	Cash, Cash Equivalents and Marketable Securities
	The Company considers all highly liquid investments with an original maturity (at date of purchase) of three months or less to be cash equivalents. Cash and cash equivalents consist of cash on deposit with banks and money market instruments.
	All marketable securities are classified as available-for-sale and consist of U.S. Treasury and U.S. government sponsored enterprise debt securities. These securities are carried at estimated fair value, which is based on quoted market prices or observable market inputs of almost identical assets, with unrealized gains and losses included in accumulated other comprehensive income (loss). The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income or expense. The cost of securities sold is based on specific identification. The Company’s investments are subject to a periodic impairment review for other-than-temporary declines in fair value. The Company’s review includes the consideration of the cause of the impairment including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. When the Company determines that the decline in fair value of an investment is below its accounting basis and this decline is other-than-temporary, it reduces the carrying value of the security it holds and records a loss in the amount of such decline.
Property, Plant and Equipment, Policy [Policy Text Block]	Property and Equipment
	Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the estimated useful life of the improvements or the remaining lease term.
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	Impairment of Long-Lived Assets
	The Company periodically assesses the impairment of long-lived assets and, if indicators of asset impairment exist, the Company assesses the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through an analysis of the undiscounted future expected operating cash flows. If impairment is indicated, the Company records the amount of such impairment for the excess of the carrying value of the asset over its estimated fair value. For example, purchased equipment and manufacturing-related facility improvements the Company has made at Patheon’s facility in Ohio, are utilized for continued research and development, and potential commercial manufacturing of our product candidates. If the Company does not receive regulatory approval for our product candidates, the Company may determine that it is no longer probable that the Company will realize the future economic benefit associated with the costs of these assets through future manufacturing activities, and if so, the Company would record an impairment charge associated with these assets. As of December 31, 2014, the Company has not written down any of its long-lived assets as a result of impairment.
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Restricted Cash
	Under the Company’s facility lease and corporate credit card agreements, the Company is required to maintain letters of credit as security for performance under these agreements. The letters of credit are secured by certificates of deposit in amounts equal to the letters of credit, which are classified as restricted cash on the balance sheet.
Contingent Put Option, Policy [Policy Text Block]	Contingent put option
	The contingent put option associated with the Company’s loan and security agreement with Hercules Technology II, L.P. and Hercules Technology Growth Capital, Inc., collectively referred to as Hercules, is recorded as a liability. Changes in the fair value of the contingent put option are recognized as interest income and other income (expense), net in the Statements of Comprehensive Loss. For additional information regarding the contingent put option, see Note 6 “Long Term Debt.”
Warrants, Policy [Policy Text Block]	Warrants
	Warrants issued in connection with the Company’s Private Placement, completed in June 2012, are recorded as liabilities as they have the potential for cash settlement upon the occurrence of certain transactions (as defined in the warrant; see Note 7 “Warrants”). Changes in the fair value of the warrants are recognized as interest income and other income (expense), net in the Statements of Comprehensive Loss.
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition
	The Company recognizes revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the fee is fixed or determinable; and collectability is reasonably assured.
Collaborative Arrangement, Accounting Policy [Policy Text Block]	Collaboration Revenue
	Collaboration revenue, which is earned under license agreements with third parties, may include nonrefundable license fees, cost reimbursements, research and development services, commercial manufacturing services, contingent development and commercial milestones and royalties.
	AcelRx accounts for multiple-element arrangements in accordance with ASC Topic 605-25, Revenue Recognition—Multiple-Element Arrangements, or ASC 605-25.The Company evaluates if the deliverables in the arrangement represent separate units of accounting. In determining the units of accounting, AcelRx evaluates certain criteria, including whether the deliverables have value to our customers on a stand-alone basis. Factors considered in this determination include whether the deliverable is proprietary to the Company, whether the customer can use the license or other deliverables for their intended purpose without the receipt of the remaining elements, whether the value of the deliverable is dependent on the undelivered items, and whether there are other vendors that can provide the undelivered items. Deliverables that meet these criteria are considered a separate unit of accounting. Deliverables that do not meet these criteria are combined and accounted for as a single unit of accounting.
	For revenue agreements with multiple-element arrangements, such as the collaboration and license agreement with Grünenthal, the Company allocates revenue to each non-contingent element based on the relative selling price of each element. When applying the relative selling price method, the Company determines the selling price for each deliverable using vendor-specific objective evidence, or VSOE, of selling price or third-party evidence, or TPE, of selling price. If neither exists the Company uses best estimated selling price, or BESP, for that deliverable. Revenue allocated is then recognized when the four basic revenue recognition criteria are met for each element.
	VSOE is based on the price charged when the element is sold separately and is the price actually charged for that deliverable. Establishing VSOE may not be possible for the elements of a license arrangement because each arrangement is unique, an arrangement typically consists of multiple elements and AcelRx has limited history of entering into license arrangements. When VSOE cannot be established, AcelRx attempts to establish the selling price of the elements of a license arrangement based on TPE. TPE is determined based on a competitor’s price for similar deliverables when sold separately. AcelRx may not be able to determine TPE for license arrangements, as they contain a significant level of differentiation such that the comparable pricing of a competitor’s license arrangement with similar functionality cannot be obtained, and AcelRx is therefore unable to reliably determine what a similar competitor’s license arrangement’s selling price would be on a standalone basis.
	When AcelRx is unable to establish the selling price of an element using VSOE or TPE, BESP is utilized in the allocation of the elements of the arrangement. The objective of the BESP is to determine the price at which AcelRx would transact a sale if the element of the license arrangement were sold on a standalone basis.
	The process for determining BESPs involves management’s judgment. AcelRx’ process considers multiple factors such as discounted cash flows, estimated direct expenses and other costs and available data, which may vary over time, depending upon the circumstances, and relate to each deliverable. If the estimated obligation period of one or more deliverables should change, the future amortization of the revenue would also change.
	AcelRx recognizes a contingent milestone payment as revenue in its entirety upon our achievement of the milestone. A milestone is substantive if the consideration earned from the achievement of the milestone (i) is consistent with performance required to achieve the milestone or the increase in value to the delivered item, (ii) relates solely to past performance and (iii) is reasonable relative to all of the other deliverables and payments within the arrangement.
Health Care Organization, Revenue Recognized Policy [Policy Text Block]	Research Grant Revenue
	In May 2011, the Company entered into an award contract with the US Army Medical Research and Materiel Command, or USAMRMC, to support the development of the Company’s new product candidate, ARX-04, a sufentanil sublingual tablet for the treatment of moderate-to-severe acute pain. The grant provides for the reimbursement of qualified expenses for research and development activities as defined under the terms of the grant agreement. Revenue under the grant agreement is recognized when the related qualified research expenses are incurred.
Research and Development Expense, Policy [Policy Text Block]	Research and Development Expenses
	Research and development costs are charged to expense when incurred. Research and development expenses include salaries, employee benefits, including stock-based compensation, consultant fees, laboratory supplies, costs associated with clinical trials and manufacturing, including contract research organization fees, other professional services and allocations of corporate costs. The Company reviews and accrues clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of patient studies and other events.
Comphrensive Loss [Policy Text Block]	Comprehensive Loss
	Comprehensive loss is comprised of net loss and other comprehensive income (loss) and is disclosed in the Statement of Comprehensive Loss. For the Company, other comprehensive income (loss) consists of changes in unrealized gains and losses on the Company’s investments.
Fair Value Measurement, Policy [Policy Text Block]	Fair Value of Financial Instruments
	The Company measures and reports its cash equivalents, investments and financial liabilities at fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability 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 fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows:
	Level I—Unadjusted quoted prices in active markets for identical assets or liabilities;
	Level II—Inputs other than quoted prices included within Level I that are observable, unadjusted 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 related assets or liabilities; and
	Level III—Unobservable inputs that are supported by little or no market activity for the related assets or liabilities.
	The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.
Income Tax, Policy [Policy Text Block]	Income Taxes
	Deferred tax assets and liabilities are measured based on differences between the financial reporting and tax basis of assets and liabilities using enacted rates and laws that are expected to be in effect when the differences are expected to reverse. The Company records a valuation allowance for the full amount of deferred assets, which would otherwise be recorded for tax benefits relating to operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not.
Share-based Compensation, Option and Incentive Plans, Director Policy [Policy Text Block]	Stock-Based Compensation
	Compensation expense for all share-based payment awards made to employees and directors, including employee stock options, restricted stock units and employee share purchases related to the 2011 Employee Stock Purchase Plan, or ESPP, is based on estimated fair values at grant date. The Company determines the grant date fair value of the awards using the Black-Scholes option-pricing model and generally recognizes the fair value as stock-based compensation expense on a straight-line basis over the vesting period of the respective awards.
	The Black-Scholes option pricing model requires inputs such as expected term, expected volatility and risk-free interest rate. These inputs are subjective and generally require significant analysis and judgment to develop. Estimates of expected life are primarily determined using the simplified method in accordance with guidance provided by the SEC. Such method was utilized as the Company did not believe its historical option exercise experience, which was limited, provided a reasonable basis upon which to estimate expected term. Volatility is derived from historical volatilities of several public companies within AcelRx’s industry that are deemed to be comparable to AcelRx’s business because AcelRx’s has insufficient history on the volatility of its common stock relative to the expected life assumptions used by the Company. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant commensurate with the expected life assumption. Further, the Company estimates forfeitures at the time of grant and revises those estimates in subsequent periods if actual forfeitures differ from those estimates.
Earnings Per Share, Policy [Policy Text Block]	Net Loss per Share of Common Stock
	The Company’s basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. The diluted net loss per share of common stock is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, convertible preferred stock, options to purchase common stock, restricted stock subject to repurchase, warrants to purchase convertible preferred stock and warrants to purchase common stock were considered to be common stock equivalents. In periods with a reported net loss, such common stock equivalents are excluded from the calculation of diluted net loss per share of common stock if their effect is antidilutive. For additional information regarding the net loss per share, see Note 11 “Net Loss per Share of Common Stock.”
Segment Reporting, Policy [Policy Text Block]	Segment Information
	The Company operates in one operating segment and has operations solely in the United States.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU 2014-15 will explicitly require management to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosure in certain circumstances. The new standard will be effective for AcelRx beginning in fiscal 2017. Earlier adoption is permitted. The Company is currently evaluating the potential impact of the adoption of ASU 2014-15.
	In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers, issued as a new Topic, Accounting Standards Codification (ASC) Topic 606.  The new revenue recognition standard provides a five-step analysis of transactions to determine when and how revenue is recognized. The core principle of the guidance is that a Company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This ASU is effective for AcelRx beginning in fiscal 2017 and can be adopted by the Company either retrospectively or as a cumulative-effect adjustment as of the date of adoption.  The Company is currently evaluating the effect that adopting this new accounting guidance will have on its results of operations, cash flows and financial position.

Note_2_Investments_and_Fair_Va1

Note 2 - Investments and Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2014
Investments And Fair Value Measurement Disclosure [Abstract]
Cash, Cash Equivalents and Investments [Table Text Block]		As of December 31, 2014
		Amortized Cost			Gross Unrealized			Gross Unrealized			Fair
					Gains			Losses			Value
	Cash and cash equivalents:
	Cash	$	60,005		$	—		$	—		$	60,005
	Money market funds		33			—			—			33
	Total cash and cash equivalents		60,038			—			—			60,038
	Marketable securities:
	U.S. government agency securities		15,316			—			(4	)		15,312
	Total marketable securities		15,316			—			(4	)		15,312
	Total cash, cash equivalents and investments	$	75,354		$	—		$	(4	)	$	75,350
		As of December 31, 2013
		Amortized Cost			Gross Unrealized			Gross Unrealized			Fair
					Gains			Losses			Value
	Cash and cash equivalents:
	Cash	$	88,390		$	—		$	—		$	88,390
	Money market funds		11			—			—			11
	Total cash and cash equivalents		88,401			—			—			88,401
	Marketable securities:
	U.S. government agency securities		15,261			1			—			15,262
	Total marketable securities		15,261			1			—			15,262
	Total cash, cash equivalents and investments	$	103,662		$	1		$	—		$	103,663
Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]		As of December 31, 2014
		Fair Value			Level I			Level II			Level III
	Assets
	Money market funds	$	33		$	33		$	—		$	—
	U.S. government agency obligations		15,312			—			15,312			—
	Total assets measured at fair value	$	15,345		$	33		$	15,312		$	—
	Liabilities
	PIPE warrant	$	5,577		$	—		$	—		$	5,577
	Contingent put option		282			—			—			282
	Total liabilities measured at fair value	$	5,859		$	—		$	—		$	5,859
		As of December 31, 2013
		Fair Value			Level I			Level II			Level III
	Assets
	Money market funds	$	11		$	11		$	—		$	—
	U.S. government agency obligations		15,262			—			15,262			—
	Total assets measured at fair value	$	15,273		$	11		$	15,262		$	—
	Liabilities
	PIPE warrant	$	13,111		$	—		$	—		$	13,111
	Contingent put option		334			—			—			334
	Total liabilities measured at fair value	$	13,445		$	—		$	—		$	13,445
Fair Value of Warrants [Table Text Block]		As of December 31,			As of December 31,
		2014			2013
	Market Price	$	6.73		$	11.31
	Exercise Price	$	3.4		$	3.4
	Risk-free interest rate		1.1	%		1.27	%
	Expected volatility		61	%		69	%
	Expected life (in years)		2.92			3.92
	Expected dividend yield		0	%		0	%
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]		Year Ended
		December 31,
		2014
	Fair value—beginning of period	$	13,445
	Change in fair value of PIPE warrants		(7,534	)
	Change in fair value of contingent put option associated with Amended Loan Agreement with Hercules		(52	)
	Fair value—end of period	$	5,859
		Year Ended
		December 31,
		2013
	Fair value—beginning of period	$	7,500
	Change in fair value of PIPE warrants		5,693
	Change in fair value of contingent put option associated with 2011 loan and security agreement with Hercules		(82	)
	Addition of contingent put option associated with 2013 loan and security agreement with Hercules		334
	Fair value—end of period	$	13,445

Note_3_Property_and_Equipment_

Note 3 - Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]		As of December 31,
		2014			2013
	Research equipment	$	2,549		$	2,014
	Leasehold improvements		4,469			1,425
	Computer equipment and software		334			189
	Construction in process		4,844			3,277
	Tooling		527			318
	Furniture and fixtures		50			59
			12,773			7,282
	Less accumulated depreciation and amortization		(2,955	)		(2,103	)
	Property and equipment, net	$	9,818		$	5,179

Note_6_Longterm_Debt_Tables

Note 6 - Long-term Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Text Block [Abstract]
Schedule of Maturities of Long-term Debt [Table Text Block]	2015	$	8,982
	2016		11,218
	2017		10,176
	Total minimum payments		30,376
	Less amount representing interest		(3,676	)
	Notes payable, gross		26,700
	Balloon payment		(1,700	)
	Unamortized discount on notes payable		(95	)
			24,905
	Less current portion of notes payable, including unamortized discount		6,859
	Notes payable, less current portion	$	18,046

Note_8_Commitments_and_Conting1

Note 8 - Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	Year Ending December 31:
	2015	$	683
	2016		717
	2017		737
	2018		62
	Total minimum payments	$	2,199

Note_10_Stockbased_Compensatio1

Note 10 - Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Note 10 - Stock-based Compensation (Tables) [Line Items]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]			Year Ended December 31,
			2014				2013				2012
	Research and development		$	2,252			$	1,657			$	998
	General and administrative			2,188				1,822				1,152
	Total		$	4,440			$	3,479			$	2,150
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]			Number				Weighted-				Weighted-			Aggregate
			of Stock Options				Average				Average			Intrinsic
			Outstanding				Exercise				Remaining			Value
							Price				Contractual
											Life (Years)
														(in thousands)
	31-Dec-11			2,395,968			$	3.08
	Granted			1,213,391				3.36
	Forfeited			(165,781	)			3.23
	Exercised			(43,767	)			2.32
	31-Dec-12			3,399,811			$	3.18
	Granted			1,958,727				5.99
	Forfeited			(17,917	)			8.82
	Exercised			(431,216	)			3.03
	31-Dec-13			4,909,405			$	4.29
	Granted			2,512,500				8.74
	Forfeited			(615,854	)			7.76
	Exercised			(439,288	)			3.9
	31-Dec-14			6,366,763			$	5.74				8.1		$	11,106
	Vested and exercisable options—December 31, 2014			2,920,611			$	3.79				7		$	8,856
	Vested and expected to vest—December 31, 2014			6,128,922			$	5.67				8.1		$	11,006
Schedule of Share Based Compensation Stock Options Outstanding and Exercisable Activity [Table Text Block]								Options Outstanding										Options Vested and Exercisable
		Exercise Prices						Number of				Weighted-Average			Weighted-Average			Shares Subject		Weighted-Average
								Stock Options				Remaining			Exercise Price per			to Stock		Exercise Price per
								Outstanding				Contractual Life			Share			Options		Share
												(Years)
		$	1.2	-	$2.56				995,304				7.3		$	2.39			995,303	$	2.39
		$	3.11	-	$5.31				2,850,209				7.4		$	4.44			1,745,726	$	4.2
		$	5.45	-	$8.18				1,190,000				9.4		$	6.52			110,207	$	5.64
		$	10.22	-	$11.71				1,331,250				9.3		$	10.32			69,375	$	10.46
									6,366,763				8.1		$	5.74			2,920,611	$	3.79
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]			Year Ended December 31,
			2014						2013					2012
	Expected term (in years)			5.25	-	6.25				5.75	-	6.25			5.75	-	6.25
	Risk-free interest rate			1.76%	-	1.92%				1.02%	-	2.96%			0.60%	-	1.74%
	Expected volatility			69	-	72%				80%					80%
	Expected dividend rate			0%						0%					0%
2011 Equity Incentive Plan [Member]
Note 10 - Stock-based Compensation (Tables) [Line Items]
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]			Number of				Weighted
			Restricted				Average
			Stock Units				Grant Date
							Fair Value
	Restricted stock units outstanding December 31, 2012			161,096			$	3.45
	Granted			—				—
	Vested			(95,331	)			(3.45	)
	Forfeited			—				—
	Restricted stock units outstanding, December 31, 2013			65,765			$	3.45
	Granted			—				—
	Vested			(65,765	)			(3.45	)
	Forfeited			—				—
	Restricted stock units outstanding, December 31, 2014			—			$	—

Note_11_Net_Loss_Per_Share_of_1

Note 11 - Net Loss Per Share of Common Stock (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]		Years Ended December 31,
		2014			2013			2012
		(in thousands, except share and per share amounts)
	Numerator:
	Net loss used to compute net loss per share
	Basic	$	(33,353	)	$	(23,426	)	$	(33,363	)
	Adjustments for change in fair value of warrant liability		(6,988	)		—			—
	Diluted	$	(40,341	)	$	(23,426	)	$	(33,363	)
	Denominator:
	Weighted average shares outstanding used to compute net loss per share:
	Basic		43,427,111			39,746,678			22,124,637
	Dilutive effect of warrants		895,186			—			—
	Diluted		44,322,297			39,746,678			22,124,637
	Net loss per share—basic	$	(0.77	)	$	(0.59	)	$	(1.51	)
	Net loss per share—diluted	$	(0.91	)	$	(0.59	)	$	(1.51	)
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]		Year Ended December 31,
		2014			2013			2012
	Stock options to purchase common stock		6,366,763			4,909,405			3,399,811
	Restricted Stock Units		—			65,765			161,096
	Common stock warrants		180,155			1,674,669			3,136,300

Note_12_Accounts_Payable_and_A1

Note 12 - Accounts Payable and Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
Schedule of Accounts Payable and Accrued Liabilities [Table Text Block]		December 31,
		2014		2013
	Accounts payable	$	2,249	$	2,341
	Accounts payable associated with property and equipment		182		—
	Accrued compensation and employee benefits		2,540		2,397
	Accrued research and development expenses		124		248
	Accrued liabilities associated with property and equipment		23		725
	Accrued liabilities associated with Grünenthal collaboration		499		—
	Professional fees		139		230
	Interest payable		196		61
	Other		133		243
	Total accounts payable and accrued liabilities	$	6,085	$	6,245

Note_14_Income_Taxes_Tables

Note 14 - Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets [Table Text Block]		December 31,			December 31,
		2014			2013
	Deferred tax assets:
	Accruals and other	$	4,446		$	2,172
	Research credits		4,413			3,553
	Net operating loss carryforward		42,330			36,279
	Section 59(e) R&D expenditures		17,083			10,339
	Total deferred tax assets		68,272			52,343
	Valuation allowance	$	(68,272	)	$	(52,343	)
	Net deferred tax assets	$	—		$	—
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]		Year Ended December 31,
		2014			2013			2012
	Tax at statutory federal rate	$	(11,392	)	$	(7,965	)	$	(11,343	)
	State tax—net of federal benefit		(2,501	)		(716	)		(1,953	)
	PIPE Warrant liability		(2,393	)		4,898			540
	General Business credits		(628	)		(1,326	)		—
	Stock Options		543			—			—
	Other		20			(80	)		807
	Change in valuation allowance		16,351			5,189			11,949
	Provision (benefit) for income taxes	$	—		$	—		$	—
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]		Year Ended December 31,
		2014			2013			2012
	Unrecognized benefit—beginning of period	$	1,341		$	810		$	748
	Gross decreases—prior period tax positions		—			221			(17	)
	Gross increases—current period tax positions		326			310			79
	Unrecognized benefit—end of period	$	1,667		$	1,341		$	810

Note_16_Unaudited_Quarterly_Fi1

Note 16 - Unaudited Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]		2014												2013
		Q1			Q2			Q3			Q4			Q1			Q2			Q3			Q4
	Revenues	$	95		$	71		$	4,825		$	226		$	940		$	407		$	548		$	27,607
	Operating Expenses	$	8,636		$	12,331		$	9,894		$	12,005		$	11,509		$	8,178		$	8,858		$	7,624
	Net income / (loss)	$	(9,631	)	$	(10,575	)	$	671		$	(13,818	)	$	(12,762	)	$	(17,447	)	$	(10,986	)	$	17,769
	Net income / (loss) per share (basic)	$	(0.22	)	$	(0.24	)	$	0.02		$	(0.32	)	$	(0.34	)	$	(0.47	)	$	(0.26	)	$	0.41
	Net income / (loss) per share (diluted)	$	(0.22	)	$	(0.30	)	$	(0.13	)	$	(0.32	)	$	(0.34	)	$	(0.47	)	$	(0.26	)	$	0.39

Note_1_Organization_and_Summar1

Note 1 - Organization and Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Impairment of Long-Lived Assets Held-for-use (in Dollars)	$0
Number of Operating Segments	1
Minimum [Member]
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member]
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life	5 years

Note_2_Investments_and_Fair_Va2

Note 2 - Investments and Fair Value Measurement (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Investments And Fair Value Measurement Disclosure [Abstract]
Available-for-Sale Securities, Gross Unrealized Gain (Loss), Accumulated in Investments	$0	$0
Available-for-sale Securities, Gross Realized Losses	0	0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities	$0	$0

Note_2_Investments_and_Fair_Va3

Note 2 - Investments and Fair Value Measurement (Details) - Summary of Cash, Cash Equivalents and Investments (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Cash and cash equivalents:
Amortized Cost	$75,354	$103,662
Gross Unrealized Gains		1
Gross Unrealized Losses	-4
Fair Value	75,350	103,663
Cash and Cash Equivalents [Member] | Cash [Member]
Cash and cash equivalents:
Amortized Cost	60,005	88,390
Fair Value	60,005	88,390
Cash and Cash Equivalents [Member] | Money Market Funds [Member]
Cash and cash equivalents:
Amortized Cost	33	11
Fair Value	33	11
Cash and Cash Equivalents [Member]
Cash and cash equivalents:
Amortized Cost	60,038	88,401
Fair Value	60,038	88,401
Marketable Securities [Member] | U.S. Government Agency Securities [Member]
Cash and cash equivalents:
Amortized Cost	15,316	15,261
Gross Unrealized Gains		1
Gross Unrealized Losses	-4
Fair Value	15,312	15,262
Marketable Securities [Member]
Cash and cash equivalents:
Amortized Cost	15,316	15,261
Gross Unrealized Gains		1
Gross Unrealized Losses	-4
Fair Value	$15,312	$15,262

Note_2_Investments_and_Fair_Va4

Note 2 - Investments and Fair Value Measurement (Details) - Fair Value of Financial Assets and Liabilities by Level within Fair Value Hierarchy (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets
Total assets measured at fair value	$15,345	$15,273
Liabilities
Total liabilities measured at fair value	5,859	13,445
PIPE Warrants [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities
Total liabilities measured at fair value		13,111
PIPE Warrants [Member]
Liabilities
Total liabilities measured at fair value		13,111
Contingent Put Option Liability [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities
Total liabilities measured at fair value	282	334
Contingent Put Option Liability [Member]
Liabilities
Total liabilities measured at fair value	282	334
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets
Total assets measured at fair value	33	11
Fair Value, Inputs, Level 1 [Member]
Assets
Total assets measured at fair value	33	11
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Obligations [Member]
Assets
Total assets measured at fair value	15,312	15,262
Fair Value, Inputs, Level 2 [Member]
Assets
Total assets measured at fair value	15,312	15,262
Fair Value, Inputs, Level 3 [Member] | PIPE Warrants [Member]
Liabilities
Total liabilities measured at fair value	5,577
Fair Value, Inputs, Level 3 [Member]
Liabilities
Total liabilities measured at fair value	5,859	13,445
PIPE Warrants [Member]
Liabilities
Total liabilities measured at fair value	5,577
Money Market Funds [Member]
Assets
Total assets measured at fair value	33	11
U.S. Government Agency Obligations [Member]
Assets
Total assets measured at fair value	$15,312	$15,262

Note_2_Investments_and_Fair_Va5

Note 2 - Investments and Fair Value Measurement (Details) - Assumptions Used in Black-Scholes Option Pricing Model to Estimate Fair Value of Pipe Warrants (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Assumptions Used in Black-Scholes Option Pricing Model to Estimate Fair Value of Pipe Warrants [Abstract]
Market Price (in Dollars per share)	$6.73	$11.31
Exercise Price (in Dollars per share)	$3.40	$3.40
Risk-free interest rate	1.10%	1.27%
Expected volatility	61.00%	69.00%
Expected life (in years)	2 years 335 days	3 years 335 days
Expected dividend yield	0.00%	0.00%

Note_2_Investments_and_Fair_Va6

Note 2 - Investments and Fair Value Measurement (Details) - Summary of Changes in Fair Value of Level III Financial Liabilities (Fair Value, Inputs, Level 3 [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value—beginning of period	$13,445	$7,500
Change in fair value of PIPE warrants	-7,534	5,693
Fair value—end of period	5,859	13,445
Amended Loan Agreement With Hercules [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of contingent put option	-52
Hercules 2011 Loan and Security Agreement [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of contingent put option		-82
Hercules 2013 Loan and Security Agreement [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of contingent put option		$334

Note_3_Property_and_Equipment_1

Note 3 - Property and Equipment (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 3 - Property and Equipment (Details) [Line Items]
Depreciation, Depletion and Amortization	$866	$593	$605
Property, Plant and Equipment, Gross	12,773	7,282
Patheon Cincinnati Facility [Member] | Construction in Progress [Member]
Note 3 - Property and Equipment (Details) [Line Items]
Property, Plant and Equipment, Gross	3,800
Construction in Progress [Member]
Note 3 - Property and Equipment (Details) [Line Items]
Property, Plant and Equipment, Gross	$4,844	$3,277

Note_3_Property_and_Equipment_2

Note 3 - Property and Equipment (Details) - Components of Property and Equipment (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$12,773	$7,282
Less accumulated depreciation and amortization	-2,955	-2,103
Property and equipment, net	9,818	5,179
Research Equipment and Facilities [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	2,549	2,014
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	4,469	1,425
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	334	189
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	4,844	3,277
Tooling [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	527	318
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$50	$59

Note_4_Research_Grant_Details

Note 4 - Research Grant (Details) (USD $)	12 Months Ended			32 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	31-May-11
Research and Development [Abstract]
Grants Receivable					$5,600,000
Revenue from Grants	$0	$2,132,000	$2,394,000	$5,600,000

Note_5_Collaboration_Details

Note 5 - Collaboration (Details) (USD $)	1 Months Ended	12 Months Ended		3 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2014
Note 5 - Collaboration (Details) [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized	$30,000,000
undefined		15,000,000
Revenue Recognition, Milestone Method, Agreed Additional Amount Based on Efforts and Targets		200,000,000
Manufacturing Agreement, Percentage for Five Years		100.00%
Manufacturing Agreement, Percentage Therafter		80.00%
Potential Milestone Payments, Related to Net Sales Target		171,500,000
Revenue Recognized Collaboration Agreement		5,217,000	27,370,000
Research and Development Services [Member]
Note 5 - Collaboration (Details) [Line Items]
Deferred Revenue, Revenue Recognized		600,000
Deferred Revenue		2,400,000
Based upon Successful Regulatory and Product Development Efforts [Member]
Note 5 - Collaboration (Details) [Line Items]
Revenue Recognition, Milestone Method, Agreed Additional Amount Based on Efforts and Targets		28,500,000
Based upon Net Sales Target Achievements [Member]
Note 5 - Collaboration (Details) [Line Items]
Revenue Recognition, Milestone Method, Agreed Additional Amount Based on Efforts and Targets		171,500,000
Zalviso [Member] | Europe [Member]
Note 5 - Collaboration (Details) [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized		20,000,000
Zalviso [Member]
Note 5 - Collaboration (Details) [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized		28,500,000
Milestone Payments Received				5,000,000
Revenue Recognized Collaboration Agreement		4,600,000
Up Front Fee [Member]
Note 5 - Collaboration (Details) [Line Items]
Licenses Revenue			$27,400,000

Note_6_Longterm_Debt_Details

Note 6 - Long-term Debt (Details) (USD $)	12 Months Ended				1 Months Ended		2 Months Ended	0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Jun. 30, 2011	Jul. 31, 2013	Dec. 16, 2013	Jun. 16, 2014	Sep. 24, 2014	Jun. 29, 2011
Note 6 - Long-term Debt (Details) [Line Items]
Debt Conversion, Converted Instrument, Warrants or Options Issued (in Shares)				274,508
Repayments of Long-term Debt		$16,345,000	$3,655,000
Gains (Losses) on Extinguishment of Debt		-1,202,000
Common Stock Warrants Exercised (in Shares)	135,000	1,135,589
Final Repayment Fee for Early Repayment of Facility	1,700,000
Fair Value of Contingent Put Option Liability	282,000	334,000			334,000
Interest Expense	2,639,000	1,518,000	2,283,000
Hercules Warrants [Member] | Hercules Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Warrant Exercisable Term				7 years
Hercules Warrants [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Warrant Exercisable Term					5 years	7 years
Debt Conversion, Converted Instrument, Warrants or Options Issued (in Shares)						274,508
Investment Warrants, Exercise Price (in Dollars per share)	$6.79				$6.79	$3.06
Common Stock Warrants Exercised (in Shares)	176,730				176,730		274,508
Prior to December 16, 2014 [Member] | Hercules Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Prepayment Charge of Term Loan, Percentage	3.00%
After December 16, 2014, but Prior to December 16, 2015 [Member] | Hercules Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Prepayment Charge of Term Loan, Percentage	2.00%
After December 16, 2015 [Member] | Hercules Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Prepayment Charge of Term Loan, Percentage	1.00%
First Tranche [Member] | Hercules Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount						10,000,000
First Tranche [Member] | Amended and Restated Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount								15,000,000
Repayments of Long-term Debt								8,600,000
Second Tranche [Member] | Hercules Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount				10,000,000
Second Tranche [Member] | Amended and Restated Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount									10,000,000
Third Tranche [Member] | Amended and Restated Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity										15,000,000
Hercules Loan and Security Agreement [Member] | Minimum [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Prepayment Charges for Accelerated Repayment of Credit Facility	1.00%
Hercules Loan and Security Agreement [Member] | Maximum [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Prepayment Charges for Accelerated Repayment of Credit Facility	3.00%
Hercules Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount											20,000,000
Number of Tranches for Loan and Security Agreement						2
Debt Instrument, Interest Rate, Stated Percentage				8.50%
Investment Warrants, Exercise Price (in Dollars per share)						$3.06
Convertible Debt	5,000,000
Debt Instrument, Convertible, Conversion Ratio, Computation, Percentage Used in Numerator	103.00%
Debt Instrument, Convertible, Conversion Ratio, Amount Used in Denominator	9.3
Additional Default Interest Rate	5.00%
Fair Value of Contingent Put Option Liability	282,000	334,000			334,000			32,000
Long-term Line of Credit	25,000,000	15,000,000	16,000,000		15,000,000
Interest Expense	2,600,000
Amortization of Debt Discount (Premium)	500,000	400,000	500,000
Amended and Restated Loan and Security Agreement [Member] | Prime Rate [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	9.10%
Debt Instrument, Basis Spread on Variable Rate	5.25%
Amended and Restated Loan and Security Agreement [Member] | Minimum [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Difference in Discounted Cash Flows, Percentage		10.00%			10.00%
Amended and Restated Loan and Security Agreement [Member]
Note 6 - Long-term Debt (Details) [Line Items]
Number of Tranches for Loan and Security Agreement								3
Line of Credit Facility, Maximum Borrowing Capacity								40,000,000
Debt Instrument, Fair Value Disclosure	24,900,000	14,300,000			14,300,000
Gains (Losses) on Extinguishment of Debt		1,200,000
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid	$1,700,000

Note_6_Longterm_Debt_Details_O

Note 6 - Long-term Debt (Details) - Outstanding Future Payments of Long-term Debt (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Outstanding Future Payments of Long-term Debt [Abstract]
2015	$8,982
2016	11,218
2017	10,176
Total minimum payments	30,376
Less amount representing interest	-3,676
Notes payable, gross	26,700
Balloon payment	-1,700
Unamortized discount on notes payable	-95
	24,905
Less current portion of notes payable, including unamortized discount	6,859
Notes payable, less current portion	$18,046	$14,364

Note_7_Warrants_Details

Note 7 - Warrants (Details) (USD $)	12 Months Ended			0 Months Ended	1 Months Ended		2 Months Ended	1 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011	Feb. 28, 2013	Dec. 31, 2013	Jun. 30, 2011	Jul. 31, 2013	Jun. 30, 2012
Note 7 - Warrants (Details) [Line Items]
Common Stock Warrants Exercised	135,000	1,135,589
Stock Issued During Period Shares Common Stock Warrants Exercised	91,488	808,078
Debt Conversion, Converted Instrument, Warrants or Options Issued			274,508
Series Warrants [Member] | Common Stock [Member]
Note 7 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding	3,425
Series B and Series C Warrants [Member] | Pinnacle Loan and Security Agreement [Member]
Note 7 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding	0
Common Stock Warrants Exercised				228,264
Stock Issued During Period Shares Common Stock Warrants Exercised				58,580
2012 Private Placement [Member]
Note 7 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding	1,359,514
Fair Value of Warrant Upon Execution of Securities Purchase Agreement (in Dollars)	5.8
Estimated Fair Value of Warrant (in Dollars)	5.6
Other Expenses (in Dollars)	7	14.1
Hercules Warrants [Member]
Note 7 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding	176,730
Common Stock Warrants Exercised	176,730				176,730		274,508
Stock Issued During Period Shares Common Stock Warrants Exercised							183,404
Investment Warrants, Exercise Price (in Dollars per share)	6.79				$6.79	$3.06
Warrant Exercisable Term					5 years	7 years
Fair Value of Warrant on Date of Issuance (in Dollars)		1.1			$1.10
Derivative, Price Risk Option Strike Price (in Dollars per Share)		6.79			$6.79
Class of Warrant or Right, Exercise Price of Warrants or Rights (in Dollars per share)		9.67			$9.67
Class of Warrant or Right Fair Value Assumption Risk Free Interest Rate		1.55%			1.55%
Class of Warrant or Right Fair Value Assumption Stock Volatility		71.00%			71.00%
Class of Warrant or Right Fair Value Assumption Expected Dividend Yield		0.00%			0.00%
Debt Conversion, Converted Instrument, Warrants or Options Issued						274,508
PIPE Warrants [Member]
Note 7 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding								2,630,103
Investment Warrants, Exercise Price (in Dollars per share)								$3.40
Warrant Exercisable Term	6 months
Warrants Vesting Condition Description	50%

Note_8_Commitments_and_Conting2

Note 8 - Commitments and Contingencies (Details) (USD $)	1 Months Ended	12 Months Ended			24 Months Ended
	31-May-14	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Mar. 31, 2012	Dec. 31, 2011
						sqft	sqft
Note 8 - Commitments and Contingencies (Details) [Line Items]
Lease Commencement Date	1-Aug-14
Operating Leases, Rent Expense		$500,000	$300,000	$300,000
Annual Product World Wide Manufacturing Requirement Percentage		80.00%
Service Agreements Expiration Date		December 31, 2017
Service Agreement Renewal Period		2 years
Agreement Termination Notice Period		18 months
Number of Products Approved		0
Manufacturing Agreement, Percentage for Five Years		100.00%
Manufacturing Agreement, Percentage Therafter		80.00%
Patheon Cincinnati Facility [Member] | Maximum [Member]
Note 8 - Commitments and Contingencies (Details) [Line Items]
Cost of Services, Overhead		200,000
Patheon Cincinnati Facility [Member] | Minimum [Member]
Note 8 - Commitments and Contingencies (Details) [Line Items]
Cost of Services, Overhead		0
Patheon Cincinnati Facility [Member]
Note 8 - Commitments and Contingencies (Details) [Line Items]
Additional Capital Expenditures Authorized Amount					480,000
Cost of Services, Overhead		$0	$0
Redwood City, California [Member]
Note 8 - Commitments and Contingencies (Details) [Line Items]
Area of Operating Lease (in Square Feet)						11,305	13,787
Lease Extended Term [Member]
Note 8 - Commitments and Contingencies (Details) [Line Items]
Area of Operating Lease (in Square Feet)	13,787
Lease Expiration Date	31-Jan-18
Additional Period of Extension in Lease Contract	5 years
Lease Expansion Space [Member]
Note 8 - Commitments and Contingencies (Details) [Line Items]
Area of Operating Lease (in Square Feet)	12,106
Lease Agreement Term	42 months

Note_8_Commitments_and_Conting3

Note 8 - Commitments and Contingencies (Details) - Future Minimum Payments Under Lease Agreement (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Future Minimum Payments Under Lease Agreement [Abstract]
2015	$683
2016	717
2017	737
2018	62
Total minimum payments	$2,199

Note_9_Stockholders_Equity_Det

Note 9 - Stockholders' Equity (Details) (USD $)

12 Months Ended

1 Months Ended

0 Months Ended

1 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

48 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Jul. 23, 2013

Jun. 30, 2012

Aug. 31, 2006

Feb. 10, 2011

Nov. 30, 2009

Feb. 29, 2008

Dec. 31, 2011

Mar. 17, 2014

Mar. 12, 2013

Mar. 26, 2012

Dec. 31, 2014

Dec. 31, 2014

19-May-14

Note 9 - Stockholders' Equity (Details) [Line Items]

Common Stock, Value Authorized to Offer and Sell (in Dollars)

$150,000,000

Common Stock, Par or Stated Value Per Share (in Dollars per share)

$0.00

0.001

0.001

Proceeds from Issuance of Class Common Stock Net of Issuance Costs (in Dollars)

47,943,000

53,174,000

Stock Issued During Period Value Underwriters Offering (in Dollars)

47,943,000

44,096,000

Public Offering [Member]

Note 9 - Stockholders' Equity (Details) [Line Items]

Stock Issued During Period, Shares, New Issues

4,370,000

Common Stock, Par or Stated Value Per Share (in Dollars per share)

$11.65

Proceeds from Issuance Initial Public Offering (in Dollars)

50,900,000

Proceeds from Issuance of Class Common Stock Net of Issuance Costs (in Dollars)

47,900,000

Stock Issued During Period Shares Underwriters New Issues

14,375,000

Common Stock Issued Under Underwritten Public Offering Price Per Share (in Dollars per share)

$3.31

Stock Issued During Period Value Underwriters Offering (in Dollars)

44,100,000

Underwriting Discount and Other Direct Costs Relating to Public Offering of Common Stock (in Dollars)

3,500,000

2012 Private Placement [Member]

Note 9 - Stockholders' Equity (Details) [Line Items]

Stock Issued During Period, Shares, New Issues

2,922,337

Warrant Issued to Purchase Common Stock

2,630,103

Gross Proceeds From Issuance of Common Stock and Warrants (in Dollars)

10,000,000

Stock Offering Costs (in Dollars)

$900,000

Stock Purchase Date

29-May-12

Common Stock Shares Issued Description

1

Warrants to Purchase Common Shares

0.9

Class of Warrant or Right, Exercise Price of Warrants or Rights (in Dollars per share)

$3.40

Offering Price Per Unit of Warrants Non Affiliated Investors (in Dollars per share)

$3.40

Offering Price Per Unit of Warrants Affiliated Investors (in Dollars per share)

$3.51

Closing Consolidated Bid Price of Common Stock (in Dollars per share)

$3.40

Minimum Bid Price Per Common Stock (in Dollars per share)

$0.11

Class of Warrant or Rights Exercisable Period from Date of Issuance

6 months

Warrant Expiry From Date of Issue

5 years

Maximum [Member] | 2006 Equity Incentive Plan [Member]

Note 9 - Stockholders' Equity (Details) [Line Items]

Common Stock Voting Rights Percentage

10.00%

Fair Value of Common Stock As Percentage of Option Exercise Price

110.00%

2006 Equity Incentive Plan [Member]

Note 9 - Stockholders' Equity (Details) [Line Items]

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Outstanding

51,693

1,875,000

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized

342,000

1,823,307

Stock Option Plan Option Reserve Annual Increase as Percentage of Outstanding Shares Allowed

4.00%

Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized

1,376,059

375,000

2011 Equity Incentive Plan [Member]

Note 9 - Stockholders' Equity (Details) [Line Items]

Common Stock, Par or Stated Value Per Share (in Dollars per share)

$0.00

$0.00

$0.00

Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized

1,722,023

1,482,201

782,711

Employee Stock Purchase Plan [Member]

Note 9 - Stockholders' Equity (Details) [Line Items]

Common Stock, Par or Stated Value Per Share (in Dollars per share)

$0.00

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized

250,000

250,000

Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized

391,355

Share Based Payment Award Number of Shares Authorized

2%

Stock Issued During Period, Shares, Employee Stock Purchase Plans

254,337

Employee Stock Purchase Plan, Shares Available for Issuance

387,018

387,018

Employee Stock Purchase Plan, Shares Issued, Weighted Average Fair Value

3.97

2.45

4.35

Note_10_Stockbased_Compensatio2

Note 10 - Stock-based Compensation (Details) (USD $)	1 Months Ended	12 Months Ended			1 Months Ended
	Mar. 31, 2011	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2015
Note 10 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares)		98,366
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in Dollars per share)		$5.57	$4.15	$2.25
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized		$13,300,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		3 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value		3,200,000	1,900,000	1,300,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value		2,300,000	3,600,000	85,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in Shares)	343,815
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in Dollars per share)	$3.45
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years	3 years
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Option Vested In Period Percentage	25.00%
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vesting Percentage Year One	25.00%
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vesting Percentage Year Two	25.00%
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vesting Percentage Year Three	25.00%
Restricted Stock or Unit Expense		$56,000	$290,000	$315,000
Restricted Stock Units (RSUs) [Member]
Note 10 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number (in Shares)		0
Subsequent Event [Member]
Note 10 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in Shares)					1,748,495

Note_10_Stockbased_Compensatio3

Note 10 - Stock-based Compensation (Details) - Employee Stock Purchase Plan (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]
Stock-based compensation expense	$4,440	$3,479	$2,150
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,252	1,657	998
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$2,188	$1,822	$1,152

Note_10_Stockbased_Compensatio4

Note 10 - Stock-based Compensation (Details) - Option Activity (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Option Activity [Abstract]
Balance	6,366,763	4,909,405	3,399,811	2,395,968
Balance	$5.74	$4.29	$3.18	$3.08
Balance	8 years 36 days
Balance	$11,106
Vested and exercisable options—December 31, 2014	2,920,611
Vested and exercisable options—December 31, 2014	$3.79
Vested and exercisable options—December 31, 2014	7 years
Vested and exercisable options—December 31, 2014	8,856
Vested and expected to vest—December 31, 2014	6,128,922
Vested and expected to vest—December 31, 2014	$5.67
Vested and expected to vest—December 31, 2014	8 years 36 days
Vested and expected to vest—December 31, 2014	$11,006
Granted	2,512,500	1,958,727	1,213,391
Granted	$8.74	$5.99	$3.36
Forfeited	-615,854	-17,917	-165,781
Forfeited	$7.76	$8.82	$3.23
Exercised	-439,288	-431,216	-43,767
Exercised	$3.90	$3.03	$2.32

Note_10_Stockbased_Compensatio5

Note 10 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Note 10 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Number of Stock Options Outstanding (in Shares)	6,366,763	4,909,405	3,399,811	2,395,968
Weighted-Average Remaining Contractual Life	8 years 36 days
Options Outstanding, Weighted-average Exercise Price per Share	$5.74	$4.29	$3.18	$3.08
Shares Subject to Stock Options (in Shares)	2,920,611
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$3.79
Exercise Price Range 1 [Member]
Note 10 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Exercise Price Range, Lower Range Limit	$1.20
Exercise Price Range, Upper Range Limit	$2.56
Number of Stock Options Outstanding (in Shares)	995,304
Weighted-Average Remaining Contractual Life	7 years 109 days
Options Outstanding, Weighted-average Exercise Price per Share	$2.39
Shares Subject to Stock Options (in Shares)	995,303
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$2.39
Exercise Price Range 2 [Member]
Note 10 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Exercise Price Range, Lower Range Limit	$3.11
Exercise Price Range, Upper Range Limit	$5.31
Number of Stock Options Outstanding (in Shares)	2,850,209
Weighted-Average Remaining Contractual Life	7 years 146 days
Options Outstanding, Weighted-average Exercise Price per Share	$4.44
Shares Subject to Stock Options (in Shares)	1,745,726
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$4.20
Exercise Price Range 3 [Member]
Note 10 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Exercise Price Range, Lower Range Limit	$5.45
Exercise Price Range, Upper Range Limit	$8.18
Number of Stock Options Outstanding (in Shares)	1,190,000
Weighted-Average Remaining Contractual Life	9 years 146 days
Options Outstanding, Weighted-average Exercise Price per Share	$6.52
Shares Subject to Stock Options (in Shares)	110,207
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$5.64
Exercise Price Range 4 [Member]
Note 10 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Exercise Price Range, Lower Range Limit	$10.22
Exercise Price Range, Upper Range Limit	$11.71
Number of Stock Options Outstanding (in Shares)	1,331,250
Weighted-Average Remaining Contractual Life	9 years 109 days
Options Outstanding, Weighted-average Exercise Price per Share	$10.32
Shares Subject to Stock Options (in Shares)	69,375
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$10.46

Note_10_Stockbased_Compensatio6

Note 10 - Stock-based Compensation (Details) - Assumptions to Calculate Fair Value of Each Employee Stock Option	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 10 - Stock-based Compensation (Details) - Assumptions to Calculate Fair Value of Each Employee Stock Option [Line Items]
Expected dividend rate	0.00%	0.00%
Minimum [Member]
Note 10 - Stock-based Compensation (Details) - Assumptions to Calculate Fair Value of Each Employee Stock Option [Line Items]
Expected term (in years)	5 years 3 months	5 years 9 months	5 years 9 months
Risk-free interest rate	1.76%	1.02%	0.60%
Expected volatility	69.00%	80.00%	80.00%
Expected dividend rate	0.00%	0.00%	0.00%
Maximum [Member]
Note 10 - Stock-based Compensation (Details) - Assumptions to Calculate Fair Value of Each Employee Stock Option [Line Items]
Expected term (in years)	6 years 3 months	6 years 3 months	6 years 3 months
Risk-free interest rate	1.92%	2.96%	1.74%
Expected volatility	72.00%

Note_10_Stockbased_Compensatio7

Note 10 - Stock-based Compensation (Details) - Summary of Restricted Stock Activity (Restricted Stock Units (RSUs) [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 10 - Stock-based Compensation (Details) - Summary of Restricted Stock Activity [Line Items]
Restricted stock units outstanding	0
2011 Equity Incentive Plan [Member]
Note 10 - Stock-based Compensation (Details) - Summary of Restricted Stock Activity [Line Items]
Restricted stock units outstanding		65,765	161,096
Restricted stock units outstanding, weighted-average grant-date fair value		$3.45	$3.45
Vested	-65,765	-95,331
Vested, weighted-average grant-date fair value	($3.45)	($3.45)

Note_11_Net_Loss_Per_Share_of_2

Note 11 - Net Loss Per Share of Common Stock (Details) - Computation of Basic and Diluted Net Loss Per Share of Common Stock (USD $)	3 Months Ended								12 Months Ended
In Thousands, except 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
Net loss used to compute net loss per share
Basic	($13,818)	$671	($10,575)	($9,631)	$17,769	($10,986)	($17,447)	($12,762)	($33,353)	($23,426)	($33,363)
Adjustments for change in fair value of warrant liability									-6,988
Diluted									($40,341)	($23,426)	($33,363)
Weighted average shares outstanding used to compute net loss per share:
Basic									43,427,111	39,746,678	22,124,637
Dilutive effect of warrants									895,186
Diluted									44,322,297	39,746,678	22,124,637
Net loss per share—basic	($0.32)	$0.02	($0.24)	($0.22)	$0.41	($0.26)	($0.47)	($0.34)	($0.77)	($0.59)	($1.51)
Net loss per share—diluted	($0.32)	($0.13)	($0.30)	($0.22)	$0.39	($0.26)	($0.47)	($0.34)	($0.91)	($0.59)	($1.51)

Note_11_Net_Loss_Per_Share_of_3

Note 11 - Net Loss Per Share of Common Stock (Details) - Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss Per Share	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock equivalents excluded from the computation of diluted net loss per share of common stock	6,366,763	4,909,405	3,399,811
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock equivalents excluded from the computation of diluted net loss per share of common stock		65,765	161,096
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock equivalents excluded from the computation of diluted net loss per share of common stock	180,155	1,674,669	3,136,300

Note_12_Accounts_Payable_and_A2

Note 12 - Accounts Payable and Accrued Liabilities (Details) - Accounts Payable and Accrued Liabilities (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Note 12 - Accounts Payable and Accrued Liabilities (Details) - Accounts Payable and Accrued Liabilities [Line Items]
Accounts payable	$2,431	$2,341
Accrued compensation and employee benefits	2,540	2,397
Accrued research and development expenses	124	248
Professional fees	139	230
Interest payable	196	61
Other	133	243
Total accounts payable and accrued liabilities	6,085	6,245
Not Associated with Property and Equipment [Member]
Note 12 - Accounts Payable and Accrued Liabilities (Details) - Accounts Payable and Accrued Liabilities [Line Items]
Accounts payable	2,249	2,341
Associated with Property and Equipment [Member]
Note 12 - Accounts Payable and Accrued Liabilities (Details) - Accounts Payable and Accrued Liabilities [Line Items]
Accounts payable	182
Accrued liablities	23	725
Associated with Grünenthal Collaboration [Member]
Note 12 - Accounts Payable and Accrued Liabilities (Details) - Accounts Payable and Accrued Liabilities [Line Items]
Accrued liablities	$499

Note_13_401k_Plan_Details

Note 13 - 401(k) Plan (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Benefit Plans [Abstract]
Defined Contribution Plan Employer Discretionary Contribution Percentage	3.00%
Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage	100.00%
Contributions By Employer to Postemployment Benefit Obligations	$201,000	$143,000	$120,000

Note_14_Income_Taxes_Details

Note 14 - Income Taxes (Details) (USD $)	1 Months Ended	12 Months Ended
	Mar. 31, 2011	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 14 - Income Taxes (Details) [Line Items]
Income Tax Expense (Benefit)		$0	$0	$0
Valuation Allowances and Reserves, Period Increase (Decrease)		16,400,000	4,800,000	11,900,000
Deferred Tax Assets Valuation Allowance Stock Based Compensation		2,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years	3 years
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Note 14 - Income Taxes (Details) [Line Items]
Tax Credit Carryforward, Amount		3,300,000
Domestic Tax Authority [Member]
Note 14 - Income Taxes (Details) [Line Items]
Operating Loss Carryforwards		109,100,000
Research and Development Credits Expiration Year		2026
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Note 14 - Income Taxes (Details) [Line Items]
Tax Credit Carryforward, Amount		1,700,000
State and Local Jurisdiction [Member]
Note 14 - Income Taxes (Details) [Line Items]
Operating Loss Carryforwards		109,100,000
Net Operating Loss Carryforwards Begins to Expire		2015
Subject to Expiration [Member] | Research Tax Credit Carryforward [Member]
Note 14 - Income Taxes (Details) [Line Items]
Tax Credit Carryforward, Amount		26,000
Subject to Expiration [Member]
Note 14 - Income Taxes (Details) [Line Items]
Operating Loss Carryforwards		$1,400,000

Note_14_Income_Taxes_Details_N

Note 14 - Income Taxes (Details) - Net Deferred Tax Assets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred tax assets:
Accruals and other	$4,446	$2,172
Research credits	4,413	3,553
Net operating loss carryforward	42,330	36,279
Section 59(e) R&D expenditures	17,083	10,339
Total deferred tax assets	68,272	52,343
Valuation allowance	($68,272)	($52,343)

Note_14_Income_Taxes_Details_R

Note 14 - Income Taxes (Details) - Reconciliation of Statutory Federal Income Tax (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Statutory Federal Income Tax [Abstract]
Tax at statutory federal rate	($11,392)	($7,965)	($11,343)
State tax—net of federal benefit	-2,501	-716	-1,953
PIPE Warrant liability	-2,393	4,898	540
General Business credits	-628	-1,326
Stock Options	543
Other	20	-80	807
Change in valuation allowance	$16,351	$5,189	$11,949

Note_14_Income_Taxes_Details_R1

Note 14 - Income Taxes (Details) - Reconciliation of Beginning and Ending Balance of Unrecognized Tax Benefits (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Beginning and Ending Balance of Unrecognized Tax Benefits [Abstract]
Unrecognized benefit—beginning of period	$1,341	$810	$748
Gross decreases—prior period tax positions		221	-17
Gross increases—current period tax positions	326	310	79
Unrecognized benefit—end of period	$1,667	$1,341	$810

Note_16_Unaudited_Quarterly_Fi2

Note 16 - Unaudited Quarterly Financial Data (Details) - Quarterly Financial Data (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 Data [Abstract]
Revenues	$226	$4,825	$71	$95	$27,607	$548	$407	$940	$5,217	$29,502	$2,394
Operating Expenses	12,005	9,894	12,331	8,636	7,624	8,858	8,178	11,509	42,866	36,169	32,107
Net income / (loss)	($13,818)	$671	($10,575)	($9,631)	$17,769	($10,986)	($17,447)	($12,762)	($33,353)	($23,426)	($33,363)
Net income / (loss) per share (basic) (in Dollars per share)	($0.32)	$0.02	($0.24)	($0.22)	$0.41	($0.26)	($0.47)	($0.34)	($0.77)	($0.59)	($1.51)
Net income / (loss) per share (diluted) (in Dollars per share)	($0.32)	($0.13)	($0.30)	($0.22)	$0.39	($0.26)	($0.47)	($0.34)	($0.91)	($0.59)	($1.51)