v3.8.0.1

Note 9 - Warrants (Details Textual) $ / shares in Units, $ in Thousands |  |  | 1 Months Ended | 6 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | ---
Sep. 18, 2015 $ / shares shares | Dec. 16, 2013 $ / shares shares | Sep. 30, 2016 USD ($) $ / shares shares | Dec. 31, 2013 USD ($) $ / shares $ / item shares | Jun. 30, 2012 USD ($) $ / shares shares | Jun. 30, 2016 $ / shares | Dec. 31, 2017 USD ($) shares | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) shares | Sep. 30, 2015 USD ($) | Sep. 17, 2015 $ / shares
Common Stock Warrants Exercised |  |  |  |  |  |  |  |  | 847,058 |  |
Stock Issued During Period, Shares, Common Stock Warrants Exercised |  |  |  |  |  |  |  |  | 527,101 |  |
2012 Private Placement [Member] |  |  |  |  |  |  |  |  |  |  |
Fair Value of Warrant Upon Execution of Securities Purchase Agreement | $ |  |  |  |  | $ 5,800 |  |  |  |  |  |
Other Expenses | $ |  |  |  |  |  |  | $ 300 | $ 600 | $ 2,100 |  |
Hercules Warrants [Member] |  |  |  |  |  |  |  |  |  |  |
Common Stock Warrants Exercised | 176,730 | 176,730 | 176,730 | 176,730 |  |  |  |  |  |  |
Investment Warrants, Exercise Price | $ / shares |  |  | $ 3.07 | $ 6.79 |  | $ 3.88 |  |  |  |  |
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares | $ 3.88 | $ 6.79 | $ 3.07 | $ 9.67 |  |  |  |  |  |  | $ 6.79
Warrant Exercisable Term |  |  |  | 5 years |  |  |  |  |  |  |
Fair Value of Warrant On Date Of Issuance | $ |  |  | $ 45 | $ 1,100 |  |  |  |  |  | $ 100 |
Derivative, Price Risk Option Strike Price | $ / item |  |  |  | 6.79 |  |  |  |  |  |  |
Class of Warrant or Right Fair Value Assumption Risk Free Interest Rate |  |  |  | 1.55% |  |  |  |  |  |  |
Class of Warrant or Right Fair Value Assumption Stock Volatility |  |  |  | 71.00% |  |  |  |  |  |  |
Class of Warrant or Right Fair Value Assumption Expected Dividend Yield |  |  |  | 0.00% |  |  |  |  |  |  |
Class of Warrant or Right, Outstanding |  |  |  |  |  |  | 176,730 |  |  |  |
PIPE Warrants [Member] |  |  |  |  |  |  |  |  |  |  |
Investment Warrants, Exercise Price | $ / shares |  |  |  |  | $ 3.40 |  |  |  |  |  |
Warrant Exercisable Term |  |  |  |  | 5 years |  |  |  |  |  |
Class of Warrant or Right, Outstanding |  |  |  |  | 2,630,103 |  | 512,456 |  |  |  |
Warrants Vesting Condition Description |  |  |  |  | 50.00% |  |  |  |  |  |

X
- Definition Represents the warrants expected dividend yield. + References No definition available. + Details
Name: | acrx_ClassOfWarrantOrRightFairValueAssumptionExpectedDividendYield
Namespace Prefix: | acrx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the warrant risk free interest rate. + References No definition available. + Details
Name: | acrx_ClassOfWarrantOrRightFairValueAssumptionRiskFreeInterestRate
Namespace Prefix: | acrx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the warrant expected stock volatility. + References No definition available. + Details
Name: | acrx_ClassOfWarrantOrRightFairValueAssumptionStockVolatility
Namespace Prefix: | acrx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents common stock warrants exercised. + References No definition available. + Details
Name: | acrx_CommonStockWarrantsExercised
Namespace Prefix: | acrx_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the fair market value of the warrant on the date that was issued. + References No definition available. + Details
Name: | acrx_FairValueOfWarrantOnDateOfIssuance
Namespace Prefix: | acrx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the fair value of warrants upon the execution of the securities purchase agreement. + References No definition available. + Details
Name: | acrx_FairValueOfWarrantUponExecutionOfSecuritiesPurchaseAgreement
Namespace Prefix: | acrx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number of shares issued for common stock warrants exercised. + References No definition available. + Details
Name: | acrx_StockIssuedDuringPeriodSharesCommonStockWarrantsExercised
Namespace Prefix: | acrx_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The warrants term. + References No definition available. + Details
Name: | acrx_WarrantExercisableTerm
Namespace Prefix: | acrx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the condition for vesting warrants. + References No definition available. + Details
Name: | acrx_WarrantsVestingConditionDescription
Namespace Prefix: | acrx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Exercise price of the warrants. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column A + Details
Name: | invest_InvestmentWarrantsExercisePrice
Namespace Prefix: | invest_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)(4)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The strike price on the price risk option contract such as a put option or a call option. + References No definition available. + Details
Name: | us-gaap_DerivativePriceRiskOptionStrikePrice
Namespace Prefix: | us-gaap_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of expense classified as other. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.7) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4,6) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_OtherExpenses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=acrx_PrivatePlacement2012Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=acrx_HerculesWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=acrx_PIPEWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |