Investments in Unconsolidated Joint Ventures - Balance Sheet footnotes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Assets	$ 9,669,584		$ 9,184,005
Liabilities	6,672,279		6,738,745
Joint Venture
Schedule of Equity Method Investments [Line Items]
Amortization of difference between cost of investments and book value of underlying equity	2,243	$ 3,999
Joint Venture | PPR Portfolio | PPR Portfolio
Schedule of Equity Method Investments [Line Items]
Assets	2,840,770		2,857,757
Liabilities	$ 1,683,155		$ 1,687,042