Fair Values - Schedule of Details of Carrying Amount, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Nov. 30, 2013
Carrying Amount [Member]
Financial assets
Cash and cash equivalents	$ 75,567	$ 96,450
Restricted cash		9,556
Loans receivable, net	8,692,978	9,077,007
Financial liabilities
Secured debt agreements, net	5,716,354	6,116,105
Loan participations sold, net	348,077	497,032
Convertible notes, net	166,762	164,026
Fair Value [Member]
Financial assets
Cash and cash equivalents	75,567	96,450
Restricted cash		9,556
Loans receivable, net	8,733,784	9,121,732
Financial liabilities
Secured debt agreements, net	5,731,626	6,131,751
Loan participations sold, net	349,633	498,992
Convertible notes, net	191,763	171,344
Cash and cash equivalents, face amount	75,567	96,450	$ 51,810	$ 52,342
Restricted cash, face amount		9,556
Loans receivable, net, face amount	8,727,218	9,108,361
Secured debt agreements, net, face amount	5,731,626	6,131,751
Loan participations sold, net	348,077	497,032
Loan participations sold, net, face amount	419,560	608,554
Senior Participation [Member]
Financial liabilities
Loan participations sold, net	348,077	497,032
Loan participations sold, net, face amount	349,633	498,992
5.25% Convertible Senior Notes [Member]
Financial liabilities
Convertible notes, net, face amount	$ 172,500	$ 172,500			$ 172,500