Loans and Preferred Equity Held for Investment, net and Loans Held for Sale - Activity in Loans Held for Investment, Net (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance at January 1, 2020			$ 2,576,332
Acquisitions/originations/additional funding		$ 66,722
Loan maturities/principal repayments		(176,021)
Transfer to loans held for sale		(154,370)
Discount accretion/premium amortization		4,289
Capitalized interest		6,382
Provision for loan losses		(75,200)
Effect of CECL adoption		(21,093)
Charge-off		15,533
Balance at end of period	$ 2,242,574	2,242,574
Provision for loan losses transferred to held for sale	5,200
PD/LGD model
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Unfunded commitments	$ 100	$ 100