Fair Values - Schedule of Details of Carrying Amount, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Financial liabilities
Loan participations sold	$ 422,585	$ 497,032
Carrying Amount [Member]
Financial assets
Cash and cash equivalents	181,796	96,450
Restricted cash	476	9,556
Loans receivable, net	9,090,934	9,077,007
Financial liabilities
Secured debt agreements	6,198,093	6,116,105
Loan participations sold	422,585	497,032
Convertible notes, net	165,373	164,026
Face Amount [Member]
Financial assets
Cash and cash equivalents	181,796	96,450
Restricted cash	476	9,556
Loans receivable, net	9,122,567	9,108,361
Financial liabilities
Secured debt agreements	6,214,882	6,131,751
Loan participations sold	424,488	498,992
Convertible notes, net	172,500	172,500
Fair Value [Member]
Financial assets
Cash and cash equivalents	181,796	96,450
Restricted cash	476	9,556
Loans receivable, net	9,147,799	9,121,732
Financial liabilities
Secured debt agreements	6,214,882	6,131,751
Loan participations sold	424,488	498,992
Convertible notes, net	$ 183,131	$ 171,344