Components of Asset-Backed Securities Issued by Consolidated Securitization Entities Sponsored, Along With Other Selected Information (Detail) (Asset-backed Securities, USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Unamortized premium	$ 1,087	$ 1,280
Unamortized discount	(4,708)	(5,655)
Fair value adjustment, net	(2,624,263)	(2,675,586)
ABS issued	3,563,873	4,139,355
Certificates With Principal Value
Debt Instrument [Line Items]
Principal value	6,177,118	6,802,412
Interest Only Certificates
Debt Instrument [Line Items]
Principal value	14,639	16,904
Sequoia
Debt Instrument [Line Items]
Unamortized premium	1,087	1,280
Unamortized discount	(4,708)	(5,655)
ABS issued	3,126,482	3,710,423
Number of series	34	39
Sequoia | Minimum
Debt Instrument [Line Items]
Weighted average interest rates, by series	0.43%	0.39%
Stated maturities	2014	2014
Sequoia | Maximum
Debt Instrument [Line Items]
Weighted average interest rates, by series	4.15%	4.15%
Stated maturities	2047	2047
Sequoia | Certificates With Principal Value
Debt Instrument [Line Items]
Principal value	3,115,464	3,697,894
Sequoia | Interest Only Certificates
Debt Instrument [Line Items]
Principal value	14,639	16,904
Acacia
Debt Instrument [Line Items]
Fair value adjustment, net	(2,624,263)	(2,675,586)
ABS issued	244,073	209,381
Number of series	10	10
Acacia | Minimum
Debt Instrument [Line Items]
Weighted average interest rates, by series	0.92%	0.76%
Stated maturities	2039	2039
Acacia | Maximum
Debt Instrument [Line Items]
Weighted average interest rates, by series	1.48%	1.94%
Stated maturities	2052	2052
Acacia | Certificates With Principal Value
Debt Instrument [Line Items]
Principal value	2,868,336	2,884,967
Resecuritization
Debt Instrument [Line Items]
ABS issued	193,318	219,551
Weighted average interest rates, by series	2.24%	2.19%
Stated maturities	2046	2046
Number of series	1	1
Resecuritization | Certificates With Principal Value
Debt Instrument [Line Items]
Principal value	$ 193,318	$ 219,551