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Stock-Based Compensation - Additional Information (Detail) (USD $)
8 Months Ended 12 Months Ended 0 Months Ended
Dec. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Mar. 11, 2015
Mar. 03, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock-based compensation $ 1,249,000us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition $ 1,285,000us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition $ 1,249,000us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition    
2013 Equity Incentive Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Aggregate shares of common stock permitted to be granted   700,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_PlanNameAxis
= ahh_TwoThousandThirteenEquityIncentivePlanMember
     
Equity Incentive Plan, term   10 years      
Shares of common stock reserved for issuance   431,049us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_PlanNameAxis
= ahh_TwoThousandThirteenEquityIncentivePlanMember
     
Subsequent Event [Member] | Non Employee Director [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Restricted stock granted       646us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
/ us-gaap_TitleOfIndividualAxis
= ahh_NonEmployeeDirectorMember
 
Restricted stock granted, grant date fair value       $ 10.36us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
/ us-gaap_TitleOfIndividualAxis
= ahh_NonEmployeeDirectorMember
 
Restricted Stock [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Restricted stock granted   132,081us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Restricted stock award, vesting period   2 years      
Restricted stock award, percentage vested on grant date   33.33%us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Restricted stock award vest grant over period   1 year      
Unrecognized compensation cost   $ 500,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Unrecognized compensation cost, recognition period   15 months      
Shares tendered by employees to satisfy minimum statutory tax withholding obligations   21,439us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Restricted stock granted, grant date fair value   $ 9.85us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Restricted Stock [Member] | Subsequent Event [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Restricted stock granted         72,282us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Restricted stock granted, grant date fair value         $ 10.98us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember