Payment Status for the LHFI Portfolio (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Loans carried at fair value	$ 360	[1]	$ 379	[1]
Nonaccruing 90 Plus Days Past Due	883		975
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Loans carried at fair value	360		379
Residential Portfolio Segment [Member] | Residential Nonguaranteed [Member]
Financing Receivable, Impaired [Line Items]
Loans carried at fair value	$ 360		$ 379

[1] 2 Includes loans of consolidated VIEs355 365