Corporate Indebtedness - Junior Subordinated Deferrable Interest Debentures and Principal Maturities (Details)	1 Months Ended	3 Months Ended
Jun. 30, 2005 USD ($)	Mar. 31, 2021 USD ($) quarter
Principal Repayments and Joint Venture Debt
Remaining 2021		$ 526,901,000
2022		1,064,200,000
2023		2,496,594,000
2024		478,029,000
2025		100,823,000
Thereafter		681,116,000
Total principal repayments		$ 5,347,663,000
Trust Preferred Securities
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 100,000,000.0
LIBOR \| Trust Preferred Securities
Debt Instrument [Line Items]
Interest rate added to base rate (as a percent)		1.25%
Interest payment deferment, number of consecutive quarters \| quarter		8
Joint venture
Principal Repayments and Joint Venture Debt
Remaining 2021		$ 1,126,896,000
2022		227,701,000
2023		491,066,000
2024		620,843,000
2025		1,403,266,000
Thereafter		552,813,000
Total principal repayments		4,422,585,000
Joint venture \| Trust Preferred Securities
Principal Repayments and Joint Venture Debt
Remaining 2021		0
2022		0
2023		0
2024		0
2025		0
Thereafter		100,000,000
Total principal repayments		100,000,000
Joint venture \| Mortgages and other loans payable
Scheduled Amortization
Remaining 2021		8,031,000
2022		8,765,000
2023		6,594,000
2024		5,280,000
2025		823,000
Thereafter		924,000
Total amortization of debt		30,417,000
Principal Repayments and Joint Venture Debt
Remaining 2021		168,870,000
2022		255,435,000
2023		560,000,000
2024		272,749,000
2025		0
Thereafter		580,192,000
Total principal repayments		1,837,246,000
Joint venture \| Revolving Credit Facility
Principal Repayments and Joint Venture Debt
Remaining 2021		0
2022		0
2023		630,000,000
2024		0
2025		0
Thereafter		0
Total principal repayments		630,000,000
Joint venture \| Unsecured Term Loans
Principal Repayments and Joint Venture Debt
Remaining 2021		0
2022		0
2023		1,300,000,000
2024		200,000,000
2025		0
Thereafter		0
Total principal repayments		1,500,000,000
Joint venture \| Senior Unsecured Notes
Principal Repayments and Joint Venture Debt
Remaining 2021		350,000,000
2022		800,000,000
2023		0
2024		0
2025		100,000,000
Thereafter		0
Total principal repayments		$ 1,250,000,000

Debt Instrument, Interest Payment Deferment, Number Of Consecutive Quarters

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The total expected future amortization of debt.

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The amount of amortization of debt expected to be recognized after the fifth full fiscal year following the date of the most recent balance sheet.

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The amount of amortization of debt expected to be recognized during the fifth full fiscal year following the date of the most recent balance sheet.

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The amount of amortization of debt expected to be recognized during the fourth full fiscal year following the date of the most recent balance sheet.

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The amount of amortization of debt expected to be recognized during the second full fiscal year following the date of the most recent balance sheet.

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The amount of amortization of debt expected to be recognized during the third full fiscal year following the date of the most recent balance sheet.

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Total amount of long-term debt maturing in future periods.

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Long Term Debt, Maturity, After Year Four

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

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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.

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in remainder of current fiscal year.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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