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Employee Benefit Plans (Details) (USD $) | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013
Defined Contribution Plan Disclosure [Line Items] |  |
Matching contribution | matching contribution equal to 100% of the employee’s first 3% of the employee’s contributions and 50% of the employee’s next 2% of contributions. |
Company's contribution | $ 108,000 us-gaap_DefinedContributionPlanCostRecognized | $ 70,000 us-gaap_DefinedContributionPlanCostRecognized
First 3% of pay contributed |  |
Defined Contribution Plan Disclosure [Line Items] |  |
Benefit Plan, Percentage of Match | 100.00%us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch / us-gaap_DefinedContributionPlanNameAxis = abio_FirstThreePercentPayContributionMember |
Employer matching contribution percentage | 3.00%us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent / us-gaap_DefinedContributionPlanNameAxis = abio_FirstThreePercentPayContributionMember |
Next 2% of pay contributed |  |
Defined Contribution Plan Disclosure [Line Items] |  |
Benefit Plan, Percentage of Match | 50.00%us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch / us-gaap_DefinedContributionPlanNameAxis = abio_NextTwoPercentPayContributionMember |
Employer matching contribution percentage | 2.00%us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent / us-gaap_DefinedContributionPlanNameAxis = abio_NextTwoPercentPayContributionMember |

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- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942 + Details
Name: | us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Percentage employer matches of the employee's percentage contribution matched. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Description of the terms and benefits provided by the employer's defined contribution plans. A defined contribution plan provides benefits in return for services rendered, provides an individual account for each participant, and has terms that specify how contributions to the individual's account are to be determined rather than the amount of benefits the individual is to receive. Under a defined contribution pension plan, the benefits a participant will receive depend solely on the amount contributed to the participant's account, the returns earned on investments of those contributions, and forfeitures of other participants' benefits that may be allocated to such participant's account. A description of the plan(s) including employee groups covered, the basis for determining contributions, and the nature and effects of significant matters affecting comparability of information for all periods presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Defined Contribution Postretirement Plan -URI http://asc.fasb.org/extlink&oid=6510416 + Details
Name: | us-gaap_DescriptionOfDefinedContributionPensionAndOtherPostretirementPlans
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_DefinedContributionPlanNameAxis=abio_FirstThreePercentPayContributionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_DefinedContributionPlanNameAxis=abio_NextTwoPercentPayContributionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |