FAIR VALUE OF FINANCIAL INSTRUMENTS (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Carrying value and estimated fair value of the financial instruments not carried at fair value on the consolidated balance sheet
Loans held for investment	$ 958,495	$ 353,500	$ 4,945
Financial Liabilities:
Convertible notes	67,815	67,289
Commercial mortgage-backed securitization debt (consolidated VIE)	395,027
Carrying Value \| Level 3
Carrying value and estimated fair value of the financial instruments not carried at fair value on the consolidated balance sheet
Loans held for investment	958,495	353,500
Financial Liabilities:
Secured financing agreements	264,419	144,256
Convertible notes	67,815	67,289
Commercial mortgage-backed securitization debt (consolidated VIE)	395,027
Estimated Fair Value \| Level 3
Carrying value and estimated fair value of the financial instruments not carried at fair value on the consolidated balance sheet
Loans held for investment	958,495	353,500
Financial Liabilities:
Secured financing agreements	264,419	144,256
Convertible notes	67,815	67,289
Commercial mortgage-backed securitization debt (consolidated VIE)	$ 395,027

Represents the carrying amount of debt issued by the Variable Interest Entity included in the reporting entity's statement of financial position.

No definition available.

+ Details

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Namespace Prefix:	acre_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Including the current and noncurrent portions, carrying amount of debt identified as being convertible into another form of financial instrument (typically the entity's common stock) as of the balance sheet date, which originally required full repayment more than twelve months after issuance or greater than the normal operating cycle of the company.

+ 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 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 3: 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(a)(2))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

+ Details

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

- Details

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

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Balance Type:	na
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- Definition

Fair value portion of contractual arrangement with a lender under which borrowings can be made up to a specific amount at any point in time.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Line-of-Credit Arrangement

-URI http://asc.fasb.org/extlink&oid=6517033

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ 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 210.7-03.1(c))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph c

-Article 7

+ Details

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