Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,049	$ 3,003
Accumulated Amortization	(1,664)	(1,724)
Valuation Allowance	(661)	(558)
Net Carrying Amount	724	721
Mortgage Servicing Rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,825	2,520
Accumulated Amortization	(1,467)	(1,281)
Valuation Allowance	(661)	(558)
Net Carrying Amount	697	681
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	180	439
Accumulated Amortization	(160)	(407)
Net Carrying Amount	20	32
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	44	44
Accumulated Amortization	(37)	(36)
Net Carrying Amount	$ 7	$ 8