Intangible Assets - Schedule of Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 253	$ 242
Mortgage servicing rights [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net	181	227
Purchased credit card relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net	62
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net	$ 10	$ 15