Future sale period for properties.

No definition available.

Name:	ahh_FutureSalePeriodForProperties
Namespace Prefix:	ahh_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Future sale period for properties in limited number of cases.

+ References

No definition available.

+ Details

Name:	ahh_FutureSalePeriodForPropertiesInLimitedNumberOfCases
Namespace Prefix:	ahh_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of gross profit between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

+ References

No definition available.

+ Details

Name:	ahh_GrossProfitFromRelatedParties
Namespace Prefix:	ahh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the period of opportunity to guarantee debt, or enter into a deficit restoration obligation from the closing of the entity's initial public offering.

+ References

No definition available.

+ Details

Name:	ahh_PeriodOfOpportunityToGuaranteeDebt
Namespace Prefix:	ahh_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of outstanding debt of the entity guaranteed by the related party.

+ References

No definition available.

+ Details

Name:	ahh_RelatedPartyGuaranteeOnOutstandingDebt
Namespace Prefix:	ahh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07.1(c))
-URI http://asc.fasb.org/extlink&oid=6488393&loc=d3e606610-122999

+ Details

Name:	us-gaap_RevenueFromRelatedParties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=us-gaap_ConstructionContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ahh_RealEstateServiceFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ahh_CostReimbursementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ahh_TaxProtectionAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ahh_OperatingPartnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_ExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Related Party Transactions - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	May 13, 2013	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Construction Contracts
Related Party Transactions
Revenue from contracts with affiliated entities		$ 0.1	$ 6.8	$ 7.4	$ 21.7
Construction Contracts \| Maximum
Related Party Transactions
Gross profit from related parties		0.1	0.3	0.4	0.8
Real Estate Service Fees
Related Party Transactions
Revenue from contracts with affiliated entities		0.0	0.0	0.0	0.0
Cost Reimbursements
Related Party Transactions
Revenue from contracts with affiliated entities		$ 0.0	$ 0.0	0.0	$ 0.0
Tax Protection Agreements \| Operating Partnership
Related Party Transactions
Period of opportunity to guarantee debt	10 years
Tax Protection Agreements \| Operating Partnership \| Executive Officers
Related Party Transactions
Guarantee of debt				$ 0.3
Tax Protection Agreements \| Maximum \| Operating Partnership
Related Party Transactions
Future sale period for properties	7 years
Future sale period for properties in limited number of cases	10 years