Debt - Mortgage Payable (Details)	6 Months Ended
Jun. 30, 2018 USD ($) property derivative loan	Dec. 31, 2017 USD ($) property
Mortgages
Debt Instrument [Line Items]
Number of properties collateralized \| property	45	42
Interest Rate Swaps
Debt Instrument [Line Items]
Derivative, notional amount	$ 50,000,000
Derivative fixed interest rate	2.80%
Interest Rate Swaps \| Mortgages
Debt Instrument [Line Items]
Number of interest rate derivatives held \| derivative	3
Derivative, notional amount	$ 86,600,000
Derivative fixed interest rate	2.75%
Core Portfolio
Debt Instrument [Line Items]
Derivative, notional amount	$ 406,356,000
Core Portfolio \| Mortgages
Debt Instrument [Line Items]
Number of notes repaid \| loan	1
Repayments of debt	$ 40,400,000
Scheduled principal payment	$ 3,500,000
Fund Portfolio \| Mortgages
Debt Instrument [Line Items]
Number of mortgage loans \| loan	4
Borrowings, amount	$ 109,500,000.0
Brandywine Portfolio \| Core Portfolio \| Mortgages
Debt Instrument [Line Items]
Debt default, amount		$ 26,300,000
Interest rate, stated percentage	6.00%
Debt default interest	5.00%
Interest owner percentage in property	22.00%
LIBOR \| Core Portfolio \| Mortgages
Debt Instrument [Line Items]
Basis spread on variable rate	1.65%
LIBOR \| Fund Portfolio \| Mortgages
Debt Instrument [Line Items]
Basis spread on variable rate	1.99%

Debt Instrument, Default Interest

No definition available.

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

- Definition

Mortgage Debt, Interest Owner Percentage in Property

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Mortgage Loans On Real Estate, Number Of Notes Repaid

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Number of Properties Collateralized

+ References

No definition available.

+ Details

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- 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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- Definition

Number of mortgage loans within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Footnote 3
-Subsection 29

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Footnote 3))
-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

+ Details

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- Definition

Amount of outstanding long-term debt or borrowing associated with any securities or credit agreement for which there has been a default in principal, interest, sinking fund, or redemption provisions, or any breach of covenant that existed at the end of the period and subsequently has not been cured.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(c))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

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-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- 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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- Definition

Amount of the required periodic payments applied to principal.

+ 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=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	debit
Period Type:	duration

- 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

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
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-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

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Balance Type:	na
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- Definition

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
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-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

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-Topic 235
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-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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Balance Type:	credit
Period Type:	duration

- Details

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- Details

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