Branch Assets and Liabilities Held for Sale - Assets and Liabilities Held for Sale for Certain Retail Branches (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets Held For Sale [Line Items]
Loans held for sale		$ 2,495
Properties and equipment, net		42
Goodwill allocated to retail branch disposal group		398
Total other branch assets held for sale		440
Total branch assets held for sale		2,935
Deposits held for sale		15,144
Other branch liabilities held for sale		11
Total branch liabilities held for sale		$ 15,155