Fair Values - Schedule of Details of Carrying Amount, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financial liabilities
Loan participations sold	$ 497,032	$ 496,080
Carrying Amount [Member]
Financial assets
Cash and cash equivalents	96,450	51,810
Restricted cash	9,556	11,591
Loans receivable, net	9,077,007	4,428,500
Financial liabilities
Secured debt agreements	6,116,105	2,353,279
Loan participations sold	497,032	496,080
Convertible notes, net	164,026	161,455
Face Amount [Member]
Financial assets
Cash and cash equivalents	96,450	51,810
Restricted cash	9,556	11,591
Loans receivable, net	9,108,361	4,462,897
Financial liabilities
Secured debt agreements	6,131,751	2,365,336
Loan participations sold	498,992	499,433
Convertible notes, net	172,500	172,500
Fair Value [Member]
Financial assets
Cash and cash equivalents	96,450	51,810
Restricted cash	9,556	11,591
Loans receivable, net	9,121,732	4,462,897
Financial liabilities
Secured debt agreements	6,131,751	2,365,336
Loan participations sold	498,992	499,433
Convertible notes, net	$ 171,344	$ 181,341