Premiums paid on derivative instruments.

No definition available.

Name:	ahh_PremiumsPaidOnDerivativeInstruments
Namespace Prefix:	ahh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ 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 B

+ Details

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Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Cap rate on an interest rate derivative such as an interest rate cap or collar. If market rates exceed the cap rate, a payment or receipt is triggered on the contract.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeCapInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

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

- Details

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Namespace Prefix:
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Balance Type:
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- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateCapMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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Namespace Prefix:
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- Details

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Derivative Financial Instruments - Additional Information (Details) - USD ($)	Apr. 23, 2018	Mar. 31, 2018	Mar. 07, 2018	Dec. 31, 2017
Derivatives
Interest rate agreement, notional amount		$ 376,033,000		$ 401,079,000
Interest Rate Swaps
Derivatives
Interest rate agreement, notional amount		56,033,000		56,079,000
Interest Rate Caps
Derivatives
Interest rate agreement, notional amount		$ 320,000,000	$ 50,000,000.0	$ 345,000,000
Strike rate			2.25%
Interest rate cap agreement, premium (less than)			$ 300,000
Operating Partnership \| Subsequent Event \| Interest Rate Swaps
Derivatives
Interest rate agreement, notional amount	$ 50,000,000
Fixed interest rate	2.783%