Summary of Carrying Value Components of Collateral for Asset-Backed Securities Issued and Outstanding (Detail) (Asset-backed Securities, USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	$ 2,573,802	$ 2,893,012
Residential Loans
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	1,998,178	2,272,812
Commercial Loans
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	270,449	283,610
Real Estate Securities
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	294,771	324,606
Restricted Cash
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	288	284
Accrued Interest Receivable
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	6,151	7,455
REO
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	3,965	4,245
Sequoia
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	2,005,752	2,281,688
Sequoia | Residential Loans
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	1,998,178	2,272,812
Sequoia | Restricted Cash
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	148	147
Sequoia | Accrued Interest Receivable
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	3,461	4,484
Sequoia | REO
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	3,965	4,245
Commercial Securitization
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	272,526	285,879
Commercial Securitization | Commercial Loans
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	270,449	283,610
Commercial Securitization | Restricted Cash
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	138	137
Commercial Securitization | Accrued Interest Receivable
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	1,939	2,132
Resecuritization
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	295,524	325,445
Resecuritization | Real Estate Securities
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	294,771	324,606
Resecuritization | Restricted Cash
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	2
Resecuritization | Accrued Interest Receivable
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral for ABS Issued	$ 751	$ 839