Fair Values - Schedule of Details of Carrying Amount, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financial liabilities
Loan participations sold	$ 476,894	$ 497,032
Carrying Amount [Member]
Financial assets
Cash and cash equivalents	110,622	96,450
Restricted cash	434	9,556
Loans receivable, net	9,313,763	9,077,007
Financial liabilities
Secured debt agreements	6,311,659	6,116,105
Loan participations sold	476,894	497,032
Convertible notes, net	164,696	164,026
Face Amount [Member]
Financial assets
Cash and cash equivalents	110,622	96,450
Restricted cash	434	9,556
Loans receivable, net	9,346,247	9,108,361
Financial liabilities
Secured debt agreements	6,329,385	6,131,751
Loan participations sold	478,661	498,992
Convertible notes, net	172,500	172,500
Fair Value [Member]
Financial assets
Cash and cash equivalents	110,622	96,450
Restricted cash	434	9,556
Loans receivable, net	9,368,855	9,121,732
Financial liabilities
Secured debt agreements	6,329,385	6,131,751
Loan participations sold	478,661	498,992
Convertible notes, net	$ 179,486	$ 171,344