Investment Securities (Gains and Losses Related to Investment Securities) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Gross realized gains from sales of available-for-sale securities	$ 11		$ 24		$ 98		$ 75
Gross realized losses from sales of available-for-sale securities	(5)	[1]	0	[1]	(87)	[1]	(46)	[1]
Gross losses from other-than-temporary impairment	(8)		(4)		(8)		(50)
Losses reclassified (from) to other comprehensive income	(2)		(2)		(12)		23
Gains (losses) related to investment securities, net	(4)		18		(9)		2
Impairment associated with expected credit losses	(8)		(1)		(8)		(14)
Impairment associated with management's intent to sell impaired securities prior to recovery in value	0		0		(6)		0
Impairment associated with adverse changes in timing of expected future cash flows	(2)		(5)		(6)		(13)
Net impairment losses recognized in consolidated statement of income	10		6		20		27
Available for sale, amortized cost	99,747				99,747				108,563
GREECE
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost			$ 91				$ 91

[1] Amount for the nine months ended September 30, 2012 represented a pre-tax loss from the sale of all of our Greek investment securities, which had an aggregate carrying value of approximately $91 million.