Business Acquisition Percentage of Voting Interests Acquired Option To Purchase Additional Interests

No definition available.

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- Definition

Represents the company's commitment to invest in a development project.

+ References

No definition available.

+ Details

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

- Definition

Represents the extension period of the loan receivable.

+ References

No definition available.

+ Details

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- Definition

Represent the future value of a real estate development project.

+ References

No definition available.

+ Details

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- Definition

Loans Receivable, Interest Rate, Stated Percentage

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Note Receivable Face Amount

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Notes Receivable Interest Reserve

+ References

No definition available.

+ Details

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

- Definition

Represents the number of residential units in a property.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number Of Rooms In Hotel

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Represents the number of stories in a building.

+ References

No definition available.

+ Details

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Namespace Prefix:	ahh_
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Balance Type:	na
Period Type:	instant

- Definition

Represents the number of times the loan receivable may be extended.

+ References

No definition available.

+ Details

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

- Definition

Percentage Of Debt Required To Be Paid

+ References

No definition available.

+ Details

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

- Definition

Represents the time period after a project's completion date in which the company can exercise the option to purchase an interest in the project.

+ References

No definition available.

+ Details

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

- Definition

Time Period After The Project Completion Date In Which The Company Can Exercise Additional Interests Purchase Option

+ References

No definition available.

+ Details

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Namespace Prefix:	ahh_
Data Type:	xbrli:durationItemType
Balance Type:	na
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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

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

- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

+ Details

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

- Definition

This element represents the carrying value of a short-term real estate loan to finance building costs. The funds are disbursed as needed or in accordance with a prearranged plan; generally, a portion of the funds is disbursed at inception and the remainder as construction progresses. The money is repaid on completion of the project, usually from the proceeds of a mortgage loan. The rate is normally higher than the prime rate, and there is usually an origination fee. The effective yield on these loans tends to be high, and the lender has a security interest in the real property. Note that there are separate concepts for the current and noncurrent portions of long-term construction loans.

+ References

+ Details

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

- Definition

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

+ References

+ Details

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

- Definition

The current amount of expenditures for a real estate project that has not yet been completed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.10)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248

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Balance Type:	credit
Period Type:	instant

- Definition

The net amount of nonoperating interest income (expense).

+ References

No definition available.

+ Details

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

- 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://www.xbrl.org/2003/role/presentationRef
-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=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Balance Type:	credit
Period Type:	instant

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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- Definition

Amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(3))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Balance Type:	debit
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- Details

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- Details

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Name:	dei_LegalEntityAxis=ahh_BeattyDevelopmentGroupMember
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- Details

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Notes Receivable (Details) ft² in Thousands				3 Months Ended		9 Months Ended		12 Months Ended
Notes Receivable (Details) ft² in Thousands	Sep. 30, 2016 USD ($)	Apr. 21, 2016 USD ($) ft² unit extension room	Oct. 15, 2015 USD ($) ft² unit story extension	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Oct. 27, 2017 USD ($)	May 15, 2017 USD ($)	Dec. 31, 2016 USD ($)	Nov. 10, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable				$ 75,522,000		$ 75,522,000						$ 59,546,000
Interest income				1,910,000	$ 1,024,000	4,966,000	$ 1,928,000
Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt instrument, interest rate			8.00%
Number of times the loan receivable may be extended (extension) \| extension			2
Notes receivable				22,000,000		22,000,000						20,700,000
Interest income				400,000	400,000	1,300,000	800,000
Loans Receivable \| Delray Beach, Florida \| Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable										$ 5,900,000
Beatty Development Group \| Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension period of loan receivable			1 year
Point Street Apartments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Future value of real estate project			$ 92,000,000
Number of stories in building (story) \| story			17
Number of residential units (unit) \| unit			289
Area of real estate property (sqft) \| ft²			18
Point Street Apartments \| Scenario, Forecast
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ownership interest percentage in properties								9.00%	79.00%
Consideration transferred								$ 3,100,000	$ 27,300,000
Time period after the project completion date in which the company can exercise purchase option								27 months	1 year
Point Street Apartments \| Financial Guarantee
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guarantor obligations, maximum exposure (up to)													$ 25,000,000.0
Point Street Apartments \| Financial Guarantee \| Letter of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit facility, amount outstanding				2,100,000		2,100,000						2,100,000
Point Street Apartments \| Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commitment to invest in a development project (up to)			$ 28,200,000.0
Ownership interest percentage in properties													88.00%
Point Street Apartments \| Maximum \| Beatty Development Group
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior construction loan (up to)													$ 67,000,000
Annapolis Junction Town Center
Accounts, Notes, Loans and Financing Receivable [Line Items]
Future value of real estate project		$ 102,000,000
Number of residential units (unit) \| unit		416
Area of real estate property (sqft) \| ft²		17
Time period after the project completion date in which the company can exercise purchase option	1 year
Number of times the loan receivable may be extended (extension) \| extension		2
Notes receivable				41,900,000		41,900,000						$ 38,900,000
Interest income				1,100,000	$ 700,000	3,100,000	$ 1,100,000
Note receivable maximum principal balance		$ 48,100,000.0
Number of hotel rooms (room) \| room		150
Noncontrolling interest ownership percentage in properties	80.00%				80.00%		80.00%
Percentage of voting interests acquired option to purchase additional interests	8.00%
Time period after the project completion date in which the company can exercise additional interests purchase option	27 months
Notes receivable interest reserve		$ 6,000,000
Annapolis Junction Town Center \| Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Debt instrument, interest rate		10.00%
Extension period of loan receivable		1 year
Annapolis Junction Town Center \| Financial Guarantee
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guarantor obligations, maximum exposure (up to)	$ 25,000,000.0				$ 25,000,000.0		$ 25,000,000.0
Annapolis Junction Town Center \| AJAO \| Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of debt required to be paid		80.00%
Annapolis Junction Town Center \| Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commitment to invest in a development project (up to)		$ 48,100,000.0
Noncontrolling interest ownership percentage in properties	88.00%				88.00%		88.00%
Annapolis Junction Town Center \| Maximum \| AJAO
Accounts, Notes, Loans and Financing Receivable [Line Items]
Senior construction loan (up to)	$ 60,000,000				$ 60,000,000		$ 60,000,000
Whole Foods Anchored Center \| Loans Receivable \| Mezzanine Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan interest at annual rate											15.00%
Whole Foods Anchored Center \| Loans Receivable \| Mezzanine Loan \| Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan interest at annual rate										15.00%
Whole Foods Anchored Center \| Loans Receivable \| Mezzanine Loan \| North Decatur Square Holdings, LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable				11,400,000		11,400,000
Interest income				$ 400,000		$ 600,000
Investment in development											$ 21,800,000.0
Whole Foods Anchored Center \| Loans Receivable \| Mezzanine Loan \| Delray Plaza Holdings, LLC \| Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in development										$ 13,100,000.0
Whole Foods Anchored Center \| Loans Receivable \| Decatur, Georgia
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in development											$ 34,000,000
Whole Foods Anchored Center \| Loans Receivable \| Delray Beach, Florida \| Subsequent Event
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment in development										$ 20,000,000