Debt and Preferred Equity Investments - Preferred Equity Investments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Preferred equity investment
Aggregate weighted average current yield (as a percent)	6.26%
Carrying Value	$ 1,153,363	$ 1,580,306
Preferred Equity, June 2022
Preferred equity investment
Future Funding Obligations	0
Senior Financing	1,712,750
Carrying Value	153,196	98,065
Preferred Equity, February 2027
Preferred equity investment
Future Funding Obligations	0
Senior Financing	250,000
Carrying Value	103,369	0
Preferred Equity, April 2021
Preferred equity investment
Future Funding Obligations	0
Senior Financing	0
Carrying Value	$ 0	142,921
Preferred equity investments
Preferred equity investment
Aggregate weighted average current yield (as a percent)	9.98%
Future Funding Obligations	$ 0
Senior Financing	1,962,750
Carrying Value	256,565	240,986
Allowance for loan loss	0	(1,750)
Total after allowance for loan loss	$ 256,565	$ 239,236