Fair Values - Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financial assets:
Loans receivable and other lending investments, net	$ 902,146	$ 988,224
Financial liabilities:
Debt obligations, net	3,068,556	3,609,086
Fair Value
Financial assets:
Loans receivable and other lending investments, net	900,000	1,000,000
Financial liabilities:
Debt obligations, net	$ 3,200,000	$ 3,500,000