Goodwill Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2008	Dec. 31, 2012
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 965
Goodwill, Impaired, Accumulated Impairment Loss		965
Commercial Banking [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss	750
Goodwill, Impaired, Accumulated Impairment Loss		750
Consumer Lending [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss	215
Goodwill, Impaired, Accumulated Impairment Loss		$ 215