Corporate Indebtedness - Junior Subordinated Deferrable Interest Debentures and Principal Maturities (Details) - USD ($)	1 Months Ended	9 Months Ended
Jun. 30, 2005	Sep. 30, 2019
Principal Repayments and Joint Venture Debt
Remaining 2019		$ 16,807,000
2020		491,748,000
2021		596,539,000
2022		1,546,882,000
2023		1,692,301,000
Thereafter		1,545,406,000
Total principal repayments		$ 5,889,683,000
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%
Joint venture
Principal Repayments and Joint Venture Debt
Remaining 2019		$ 10,700,000
2020		804,143,000
2021		704,174,000
2022		268,968,000
2023		311,452,000
Thereafter		1,831,026,000
Total principal repayments		3,930,463,000
Joint venture \| Trust Preferred Securities
Principal Repayments and Joint Venture Debt
Remaining 2019		0
2020		0
2021		0
2022		0
2023		0
Thereafter		100,000,000
Total principal repayments		100,000,000
Joint venture \| Mortgages and other loans payable
Scheduled Amortization
Remaining 2019		2,307,000
2020		11,118,000
2021		11,638,000
2022		9,430,000
2023		7,301,000
Thereafter		9,290,000
Total amortization of debt		51,084,000
Principal Repayments and Joint Venture Debt
Remaining 2019		14,500,000
2020		230,630,000
2021		234,901,000
2022		737,452,000
2023		50,000,000
Thereafter		1,136,116,000
Total principal repayments		2,403,599,000
Joint venture \| Revolving Credit Facility
Principal Repayments and Joint Venture Debt
Remaining 2019		0
2020		0
2021		0
2022		0
2023		335,000,000
Thereafter		0
Total principal repayments		335,000,000
Joint venture \| Unsecured Term Loans
Principal Repayments and Joint Venture Debt
Remaining 2019		0
2020		0
2021		0
2022		0
2023		1,300,000,000
Thereafter		200,000,000
Total principal repayments		1,500,000,000
Joint venture \| Senior Unsecured Notes
Principal Repayments and Joint Venture Debt
Remaining 2019		0
2020		250,000,000
2021		350,000,000
2022		800,000,000
2023		0
Thereafter		100,000,000
Total principal repayments		$ 1,500,000,000

The total expected future amortization of debt.

No definition available.

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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 after the fifth 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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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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 fifth 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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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 fourth 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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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
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
-Paragraph 14
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