Fair Values - Schedule of Details of Carrying Amount, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financial assets
Loans receivable, net		$ 19,000
Financial liabilities
Secured debt agreements	$ 7,088,738	2,365,336
Loan participations sold	635,581	499,433
Carrying Amount [Member]
Financial assets
Cash and cash equivalents	104,252	51,810
Restricted cash	7,025	11,591
Loans receivable, net	10,131,323	4,428,500
Financial liabilities
Secured debt agreements	7,088,738	2,040,783
Loan participations sold	635,581	499,433
Convertible notes, net	163,073	161,853
Face Amount [Member]
Financial assets
Cash and cash equivalents	104,252	51,810
Restricted cash	7,025	11,591
Loans receivable, net	10,169,609	4,462,897
Financial liabilities
Secured debt agreements	7,088,738	2,040,783
Loan participations sold	635,581	499,433
Convertible notes, net	172,500	172,500
Fair Value [Member]
Financial assets
Cash and cash equivalents	104,252	51,810
Restricted cash	7,025	11,591
Loans receivable, net	10,154,374	4,462,897
Financial liabilities
Secured debt agreements	7,088,738	2,040,783
Loan participations sold	635,581	499,433
Convertible notes, net	$ 185,006	$ 181,341