Represents the high end of the range of estimated fair value for investments in mortgage loans on real estate.

No definition available.

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Period Type:	instant

- Definition

Represents the low end of the range of estimated fair value for investments in mortgage loans on real estate.

+ References

No definition available.

+ Details

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- Definition

The portion of the carrying amount of long-term secured loans outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

No definition available.

+ Details

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

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
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-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

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- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-SubTopic 20
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-Paragraph 4D
-Subparagraph (c)(2)
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+ Details

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

- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Topic 210
-SubTopic 20
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-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226000-175313

+ Details

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

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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

- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ References

No definition available.

+ Details

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

- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

No definition available.

+ Details

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

- 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

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Period Type:	instant

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- Details

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- Details

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- Details

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Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Fair Value of Financial Instruments
Marketable securities	$ 85,110		$ 45,138
Interest rate cap and swap agreements (included in other assets)	21,090		204
Interest rate cap and swap agreements (included in accrued interest payable and other liabilities)	1		10,776
Debt and preferred equity investments	1,640,412		1,670,020
Secured Debt, Bearing Variable Interest, Amount	622,585		1,205,494
248-252 Bedford Avenue
Fair Value of Financial Instruments
Secured Debt, Bearing Variable Interest, Amount	0		29,000
Carrying Value (1)
Fair Value of Financial Instruments
Fixed rate debt	5,452,084		7,232,254
Variable rate debt	1,105,585		3,202,494
Total	6,557,669		10,434,748
Fair Value
Fair Value of Financial Instruments
Marketable securities	85,110		45,138
Total	6,832,604		10,770,574
Estimated fair value of debt and preferred equity investments, low end of range	1,600,000		1,700,000
Estimated fair value of debt and preferred equity investments, high end of range	1,800,000		1,800,000
Level 1
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	0		0
Interest rate cap and swap agreements (included in accrued interest payable and other liabilities)	0		0
Level 2
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	21,090		204
Interest rate cap and swap agreements (included in accrued interest payable and other liabilities)	1		10,776
Level 3
Fair Value of Financial Instruments
Marketable securities	0		0
Interest rate cap and swap agreements (included in other assets)	0		0
Interest rate cap and swap agreements (included in accrued interest payable and other liabilities)	0		0
Level 3 \| Carrying Value (1)
Fair Value of Financial Instruments
Debt and preferred equity investments			1,670,020
Level 3 \| Fair Value
Fair Value of Financial Instruments
Fixed rate debt	5,722,494		7,591,388
Variable rate debt	1,110,110		3,179,186
Equity marketable securities
Fair Value of Financial Instruments
Marketable securities		$ 48,315	4,704
Equity marketable securities \| Level 1
Fair Value of Financial Instruments
Marketable securities	48,315		4,704
Mortgage-backed securities
Fair Value of Financial Instruments
Marketable securities		$ 36,795	40,434
Mortgage-backed securities \| Level 2
Fair Value of Financial Instruments
Marketable securities	36,795		$ 40,434
248-252 Bedford Avenue \| Carrying Value (1)
Fair Value of Financial Instruments
Variable rate debt	$ 29,000