Payment Status for the LHFI Portfolio (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Loans carried at fair value	$ 379	[1]	$ 433	[1]
Nonaccruing 90 Plus Days Past Due	975		2,300
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Loans carried at fair value	379		431
Residential Portfolio Segment [Member] | Residential Nonguaranteed [Member]
Financing Receivable, Impaired [Line Items]
Loans carried at fair value	$ 379		$ 431

[1] 2 Includes loans of consolidated VIEs365 3,322