Fair Values - Schedule of Details of Carrying Amount, Face Amount, and Approximate Fair Value of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financial assets
Loans receivable, net	$ 66,063
Financial liabilities
Repurchase obligations	643,000
Carrying Amount [Member]
Financial assets
Cash and cash equivalents	10,283	15,423
Restricted cash	76,396	14,246
Loans receivable, net	1,362,891	141,500
Financial liabilities
Secured notes	9,030	8,497
Repurchase obligations	643,040
Securitized debt obligations	74,203	139,184
Face Amount [Member]
Financial assets
Cash and cash equivalents	10,283	15,423
Restricted cash	76,396	14,246
Loans receivable, net	1,387,067	164,180
Financial liabilities
Secured notes	9,030	8,497
Repurchase obligations	643,040
Securitized debt obligations	74,203	139,184
Fair Value [Member]
Financial assets
Cash and cash equivalents	10,283	15,423
Restricted cash	76,396	14,246
Loans receivable, net	1,360,842	133,682
Financial liabilities
Secured notes	8,068	7,374
Repurchase obligations	643,040
Securitized debt obligations	$ 57,138	$ 89,880