Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value of Financial Instruments
Marketable securities	$ 39,339	$ 45,138
Interest rate cap and swap agreements (included in other assets)	0	204
Debt and preferred equity investments	1,357,181	1,670,020
Accrued Interest Payable And Other Liabilities
Fair Value of Financial Instruments
Interest rate cap and swap agreements	3,036	10,776
Liabilities Held for Sale
Fair Value of Financial Instruments
Interest rate cap and swap agreements	0
Carrying Value
Fair Value of Financial Instruments
Debt and preferred equity investments	1,357,181
Fixed rate debt	6,612,587	7,232,254
Variable rate debt	1,451,155	3,202,494
Total	8,063,742	10,434,748
Fair Value
Fair Value of Financial Instruments
Marketable securities	39,339	45,138
Total	8,504,174	10,770,574
Estimated fair value of debt and preferred equity investments, low end of range	1,400,000	1,700,000
Estimated fair value of debt and preferred equity investments, high end of range	1,500,000	1,800,000
Level 1
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	0	0
Level 1 \| Accrued Interest Payable And Other Liabilities
Fair Value of Financial Instruments
Interest rate cap and swap agreements	0	0
Level 1 \| Liabilities Held for Sale
Fair Value of Financial Instruments
Interest rate cap and swap agreements	0
Level 2
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	0	204
Level 2 \| Accrued Interest Payable And Other Liabilities
Fair Value of Financial Instruments
Interest rate cap and swap agreements	3,036	10,776
Level 2 \| Liabilities Held for Sale
Fair Value of Financial Instruments
Interest rate cap and swap agreements	0
Level 3
Fair Value of Financial Instruments
Marketable securities	0	0
Interest rate cap and swap agreements (included in other assets)	0	0
Level 3 \| Accrued Interest Payable And Other Liabilities
Fair Value of Financial Instruments
Interest rate cap and swap agreements	0	0
Level 3 \| Liabilities Held for Sale
Fair Value of Financial Instruments
Interest rate cap and swap agreements	0
Level 3 \| Fair Value
Fair Value of Financial Instruments
Fixed rate debt	7,058,553	7,591,388
Variable rate debt	1,445,621	3,179,186
Equity marketable securities
Fair Value of Financial Instruments
Marketable securities	334	4,704
Equity marketable securities \| Level 1
Fair Value of Financial Instruments
Marketable securities	334	4,704
Commercial mortgage-backed securities
Fair Value of Financial Instruments
Marketable securities	39,005	40,434
Commercial mortgage-backed securities \| Level 2
Fair Value of Financial Instruments
Marketable securities	$ 39,005	$ 40,434

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

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

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No definition available.

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

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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.

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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.

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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.

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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.

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