Debt and Preferred Equity Investments - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2020 USD ($) investment	Dec. 31, 2020 USD ($) investment segment	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Jan. 01, 2020 USD ($)
Preferred equity investment
Number of investments, nonperforming | investment	1	1
Carrying value	$ 1,076,542	$ 1,076,542	$ 1,580,306
Number of portfolio segments of financial receivables (segment) | segment		1	1
Additional amount of financing receivables included in other assets	66,200	$ 66,200	$ 131,100
Current period provision for loan loss		20,693	0	$ 6,839
Financing receivable, nonaccrual status	2,500	2,500
Cumulative Effect, Period of Adoption, Adjustment
Preferred equity investment
Additional amount of financing receivables included in other assets					$ 11,400
Current period provision for loan loss	14,600
Total floating rate
Preferred equity investment
Carrying value	352,460	352,460	$ 841,660
Mortgage/Mezzanine Loan Due March 2020 | Total floating rate
Preferred equity investment
Carrying value	$ 6,800	$ 6,800