Branch Assets and Liabilities Held for Sale - Assets and Liabilities Held for Sale for Certain Retail Branches (Parenthetical) (Detail) (USD $)	Dec. 31, 2011
Assets Held For Sale [Line Items]
Branch loan held for sale commercial	$ 521,000,000
Branch loan held for sale residential mortgages	1,400,000,000
Branch loan held for sale credit card loans	416,000,000
Branch loan held for sale other consumer loans	$ 161,000,000