Goodwill and Other Intangible Assets (Identifiable Intangible Assets) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Gross carrying amount	$ 1,769		$ 1,413
Accumulated amortization	(1,051)		(969)
Net carrying amount	718		444
Core Deposit Intangibles [Member]
Gross carrying amount	688		626
Accumulated amortization	(513)		(484)
Net carrying amount	175		142
Other Identifiable Intangible Assets [Member]
Gross carrying amount	1,081	[1]	787	[1]
Accumulated amortization	(538)	[1]	(485)	[1]
Net carrying amount	$ 543	[1]	$ 302	[1]

[1] Other identifiable intangibles are primarily customer relationship intangibles.