Other Assets and Liabilities - Summary of Components of Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Accrued interest receivable	$ 32,871	$ 37,161
Loan portfolio payments held by servicer	6,294	122,666
Derivative assets	4,086	8,657
Prepaid expenses	803	890
Prepaid taxes	16	525
Real estate debt and equity investments, at fair value		14,220
Total	$ 44,070	$ 184,119