Residential Loans at Amortized Cost, Net - Aging of Past Due Residential Loans Portfolio Accounted for at Amortized Cost (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 501,908	$ 1,235,929
Total	540,708	1,324,572
Total Past Due	38,800	88,643
Non- Accrual Loans	23,130	55,663
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	11,706	24,096
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,964	8,884
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 23,130	$ 55,663