Investments in Unconsolidated Joint Ventures - Balance Sheet footnotes (Details) - Joint Venture - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Total assets	$ 10,166,921		$ 10,196,707
Amortization of difference between cost of investments and book value of underlying equity	3,999	$ 4,539
PPR Portfolio
Schedule of Equity Method Investments [Line Items]
Total assets	2,911,512		2,932,401
Total liabilities	$ 1,709,593		$ 1,732,976