Investments in Real Estate Partnerships - Scheduled Principal Repayments on Notes Payable (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
2022	$ 17,237
2023	74,071
2024	345,591
2025	293,732
2026	291,922
Beyond 5 Years	2,719,895
Unamortized debt premium/(discount) and issuance costs	(23,504)
Total	3,718,944	$ 3,923,084
Unsecured Debt [Member]
Schedule of Equity Method Investments [Line Items]
Total	3,243,991	$ 3,239,609
Unconsolidated Investments in Partnership [Member]
Schedule of Equity Method Investments [Line Items]
2022	269,929
2023	174,864
2024	35,567
2025	139,249
2026	127,757
Beyond 5 Years	706,202
Unamortized debt premium/(discount) and issuance costs	(8,701)
Total	1,444,867
Unconsolidated Investments in Partnership [Member] \| Mortgages [Member] \| Scheduled Principal Payments [Member]
Schedule of Equity Method Investments [Line Items]
2022	7,736
2023	3,256
2024	1,877
2025	2,249
2026	2,471
Beyond 5 Years	8,723
Unamortized debt premium/(discount) and issuance costs	0
Total	26,312
Unconsolidated Investments in Partnership [Member] \| Mortgages [Member] \| Mortgage Loan Maturities [Member]
Schedule of Equity Method Investments [Line Items]
2022	254,893
2023	171,608
2024	33,690
2025	137,000
2026	125,286
Beyond 5 Years	697,479
Unamortized debt premium/(discount) and issuance costs	(8,701)
Total	1,411,255
Unconsolidated Investments in Partnership [Member] \| Unsecured Debt [Member] \| Unsecured Maturities [Member]
Schedule of Equity Method Investments [Line Items]
2022	7,300
2023	0
2024	0
2025	0
2026	0
Beyond 5 Years	0
Unamortized debt premium/(discount) and issuance costs	0
Total	7,300
Unconsolidated Investments in Partnership, Pro-rata Share [Member] [Member]
Schedule of Equity Method Investments [Line Items]
2022	98,932
2023	65,149
2024	14,233
2025	42,169
2026	41,768
Beyond 5 Years	257,620
Unamortized debt premium/(discount) and issuance costs	(3,080)
Total	$ 516,791

Amount, after accumulated amortization, of debt discount (premium).

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