Goodwill and Other Intangible Assets - Changes in the Carrying Amounts of Other Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011
Beginning Balance	$ 1,017		$ 1,571
Amortization	(31)		(34)
MSRs originated	244		183
Changes in fair value:
Due to changes in inputs or assumptions	(157)	[1]	(443)	[1]
Due to fair value election	(173)	[2]	(139)	[2]
Sale of MSRs	4		7
Other			(7)
Ending Balance	896		1,138
Core Deposits
Beginning Balance	38		67
Amortization	(17)		(23)
MSRs originated	0		0
Changes in fair value:
Due to changes in inputs or assumptions	0		0
Due to fair value election	0		0
Sale of MSRs	0		0
Other			0
Ending Balance	21		44
Mortgage Servicing Rights, Amortized Cost
Beginning Balance	921		1,439
Amortization	0		0
MSRs originated	244		183
Changes in fair value:
Due to changes in inputs or assumptions	(157)	[1]	(443)	[1]
Due to fair value election	(173)	[2]	(139)	[2]
Sale of MSRs	4		7
Other			0
Ending Balance	831		1,033
Other Intangible Assets
Beginning Balance	58		65
Amortization	(14)		(11)
MSRs originated	0		0
Changes in fair value:
Due to changes in inputs or assumptions	0		0
Due to fair value election	0		0
Sale of MSRs	0		0
Other			(7)
Ending Balance	$ 44		$ 61

[1] Primarily reflects changes in discount rates and prepayment speed assumptions, due to changes in interest rates.

[2] Represents changes due to the collection of expected cash flows, net of accretion, due to the passage of time.