Corporate Indebtedness - Junior Subordinated Deferrable Interest Debentures and Principal Maturities (Details)	1 Months Ended	9 Months Ended
Jun. 30, 2005 USD ($)	Sep. 30, 2020 USD ($) quarter
Principal Repayments and Joint Venture Debt
Remaining 2020		$ 18,158,000
2021		631,240,000
2022		1,064,214,000
2023		2,491,542,000
2024		478,043,000
Thereafter		781,525,000
Total principal repayments		$ 5,464,722,000
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 2020		$ 10,867,000
2021		1,444,277,000
2022		268,952,000
2023		311,436,000
2024		618,140,000
Thereafter		1,935,202,000
Total principal repayments		4,588,874,000
Joint venture \| Trust Preferred Securities
Principal Repayments and Joint Venture Debt
Remaining 2020		0
2021		0
2022		0
2023		0
2024		0
Thereafter		100,000,000
Total principal repayments		100,000,000
Joint venture \| Mortgages and other loans payable
Scheduled Amortization
Remaining 2020		2,635,000
2021		10,766,000
2022		8,779,000
2023		6,608,000
2024		5,294,000
Thereafter		1,779,000
Total amortization of debt		35,861,000
Principal Repayments and Joint Venture Debt
Remaining 2020		15,523,000
2021		270,474,000
2022		255,435,000
2023		994,934,000
2024		272,749,000
Thereafter		579,746,000
Total principal repayments		2,388,861,000
Joint venture \| Revolving Credit Facility
Principal Repayments and Joint Venture Debt
Remaining 2020		0
2021		0
2022		0
2023		190,000,000
2024		0
Thereafter		0
Total principal repayments		190,000,000
Joint venture \| Unsecured Term Loans
Principal Repayments and Joint Venture Debt
Remaining 2020		0
2021		0
2022		0
2023		1,300,000,000
2024		200,000,000
Thereafter		0
Total principal repayments		1,500,000,000
Joint venture \| Senior Unsecured Notes
Principal Repayments and Joint Venture Debt
Remaining 2020		0
2021		350,000,000
2022		800,000,000
2023		0
2024		0
Thereafter		100,000,000
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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Future Amortization of Debt, Remainder Of Fiscal Year

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

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

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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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
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