Name:	slg_FinancingReceivableAllowanceForCreditLossesWriteOffsAndReclassifications
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Balance Type:	credit
Period Type:	duration

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Name:	us-gaap_AllowanceForLoanAndLeaseLossesRealEstate
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Balance Type:	credit
Period Type:	instant

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
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Period Type:	duration

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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-Paragraph 1
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