Debt Instrument, Floor Interest Rate

No definition available.

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Period Type:	instant

- Definition

Line Of Credit Facility, Accordion Feature, Maximum Borrowing Capacity

+ References

No definition available.

+ Details

Name:	ahh_LineOfCreditFacilityAccordionFeatureMaximumBorrowingCapacity
Namespace Prefix:	ahh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line Of Credit Facility, Duration Of Extension Option

+ References

No definition available.

+ Details

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

- Definition

Line Of Credit Facility, Extension Fee Percentage

+ References

No definition available.

+ Details

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Namespace Prefix:	ahh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line Of Credit Facility, Number Of Extension Options

+ References

No definition available.

+ Details

Name:	ahh_LineOfCreditFacilityNumberOfExtensionOptions
Namespace Prefix:	ahh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Long-Term Debt, Increase (Decease)

+ References

No definition available.

+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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-Topic 942
-SubTopic 210
-Section S99
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-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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-Name Accounting Standards Codification
-Topic 944
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-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The effective interest rate at the end of the reporting period.

+ References

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from borrowings to finance the cost of construction.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
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+ Details

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

- Details

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- Details

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- Details

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Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Indebtedness - Additional Information (Details)					3 Months Ended
Indebtedness - Additional Information (Details)	Mar. 08, 2021 USD ($)	Jan. 28, 2021 USD ($)	Jan. 15, 2021 USD ($)	Oct. 03, 2019 USD ($) extension	Mar. 31, 2021 USD ($)	Jan. 07, 2021 USD ($)	Dec. 31, 2020 USD ($)
Indebtedness
Long-term debt					$ 975,147,000		$ 963,845,000
Harbor Point Parcel 3 Partnership
Indebtedness
Credit facility, amount outstanding						$ 15,000,000.0
Minimum \| Revolving Credit Facility
Indebtedness
Basis points on unused commitment fee					0.15%
Maximum \| Revolving Credit Facility
Indebtedness
Basis points on unused commitment fee					0.25%
Construction loans
Indebtedness
Borrowings under construction loans					$ 1,800,000
Operating Partnership
Indebtedness
Credit facility, amount outstanding					9,500,000
Operating Partnership \| New Credit Facility
Indebtedness
Aggregate capacity under the credit facility				$ 355,000,000.0
Operating Partnership \| New Credit Facility \| Revolving Credit Facility
Indebtedness
Aggregate capacity under the credit facility				150,000,000.0	118,000,000
Accordion feature maximum borrowing capacity				$ 700,000,000.0
Number of extension options \| extension				2
Duration of extension option				6 months
Extension fee percentage				0.075%
Line of credit, amount outstanding					$ 10,000,000.0		10,000,000.0
Interest rate on credit facility as of end of period					1.61%
Operating Partnership \| New Credit Facility \| Term Loan Facility
Indebtedness
Aggregate capacity under the credit facility				$ 205,000,000.0
Line of credit, amount outstanding					$ 205,000,000.0		$ 205,000,000.0
Interest rate on credit facility as of end of period					1.56%
Operating Partnership \| New Credit Facility \| Minimum \| Revolving Credit Facility \| LIBOR
Indebtedness
Stated interest rate, basis spread on variable rate					1.30%
Operating Partnership \| New Credit Facility \| Minimum \| Term Loan Facility \| LIBOR
Indebtedness
Stated interest rate, basis spread on variable rate					1.25%
Operating Partnership \| New Credit Facility \| Maximum \| Revolving Credit Facility \| LIBOR
Indebtedness
Stated interest rate, basis spread on variable rate					1.85%
Operating Partnership \| New Credit Facility \| Maximum \| Term Loan Facility \| LIBOR
Indebtedness
Stated interest rate, basis spread on variable rate					1.80%
4525 Main Street and Encore Apartments
Indebtedness
Increase long term debt			$ 1,500,000
Loan interest rate			2.93%
Long-term debt			$ 57,000,000.0
Nexton Square
Indebtedness
Repayments of long-term debt		$ 2,000,000.0
Long-term debt		$ 20,100,000
Floor interest rate		0.25%
Nexton Square \| LIBOR
Indebtedness
Stated interest rate, basis spread on variable rate		2.25%
Delray Beach Plaza \| Secured Debt
Indebtedness
Long-term debt	$ 14,500,000
Delray Beach Plaza \| Secured Debt \| LIBOR
Indebtedness
Stated interest rate, basis spread on variable rate	3.00%