Derivative Financial Instruments (Notional Amount Of Interest Rate Swap Agreements Designated As Fair Value And Cash Flow Hedges) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2012		Dec. 31, 2011
Derivative [Line Items]
Notional Amount of Fair Value Hedges	$ 3,655		$ 3,748
Notional Amount of Cash Flow Hedges	129		124
Notional Amount of Derivatives	3,784		3,872
Increase in carrying value of long-term debt	190		140
Investment Securities Available For Sale [Member]
Derivative [Line Items]
Notional Amount of Fair Value Hedges	1,205		1,298
Notional Amount of Cash Flow Hedges	129		124
Notional Amount of Derivatives	1,334		1,422
Long-Term Debt [Member]
Derivative [Line Items]
Notional Amount of Fair Value Hedges	2,450	[1]	2,450	[1]
Notional Amount of Cash Flow Hedges	0	[1]	0	[1]
Notional Amount of Derivatives	$ 2,450	[1]	$ 2,450	[1]

[1] As of September 30, 2012 and December 31, 2011, fair value hedges of long-term debt increased the carrying value of long-term debt presented in our consolidated statement of condition by $190 million and $140 million, respectively.