Fair Values - Schedule of Details of Carrying Amount, Face Amount, and Fair Value of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financial assets
Loans receivable, net	$ 38,500	$ 40,700
Financial liabilities
Repurchase obligations	1,500,000
Carrying Amount [Member]
Financial assets
Cash and cash equivalents	70,834	52,342
Restricted cash	10,677	10,096
Loans receivable, net	2,710,159	2,047,223
Financial liabilities
Repurchase obligations	1,529,788	1,109,353
Convertible notes, net	160,094	159,524
Securitized debt obligations	39,394	40,181
Participations sold	90,000	90,000
Face Amount [Member]
Financial assets
Cash and cash equivalents	70,834	52,342
Restricted cash	10,677	10,096
Loans receivable, net	2,743,797	2,076,411
Financial liabilities
Repurchase obligations	1,529,788	1,109,353
Convertible notes, net	172,500	172,500
Securitized debt obligations	39,394	40,181
Participations sold	90,000	90,000
Fair Value [Member]
Financial assets
Cash and cash equivalents	70,834	52,342
Restricted cash	10,677	10,096
Loans receivable, net	2,723,534	2,058,699
Financial liabilities
Repurchase obligations	1,529,788	1,109,353
Convertible notes, net	189,578	181,772
Securitized debt obligations	26,471	25,696
Participations sold	$ 90,303	$ 90,304