Business and Organization - Additional Information (Details)	Dec. 31, 2017	Dec. 31, 2016
Business and Organization
Percentage of operating partnerships held	72.00%	68.10%
General Partner
Business and Organization
Percentage of operating partnerships held	0.10%

Percentage of ownership interests in operating partnership.

No definition available.

Name:	ahh_PercentageOfOwnershipInterestsInOperatingPartnership
Namespace Prefix:	ahh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant