Shareholders' Equity (Adjustments to Accumulated Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2014	Jun. 30, 2013
Class of Stock [Line Items]
Net interest revenue	$ 561		$ 596		$ 1,116	$ 1,172
Net gains (losses) from sales of available-for-sale securities					(15)	(5)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	46		(55)		73	(303)
Total reclassifications out of AOCI	602		571		958	1,026
Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Total reclassifications out of AOCI	13		10		10	16
Net Unrealized Gains (Losses) on Cash Flow Hedges | Interest-rate contracts | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Net interest revenue	0		1		1	2
Net Unrealized Gains (Losses) on Available-for-Sale Securities | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Net gains (losses) from sales of available-for-sale securities					(9)	(3)
Gain (Loss) on Investments, Excluding Other than Temporary Impairments, Tax		(6)		(2)
Other-Than-Temporary Impairment on Held-to-Maturity Securities | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	0		4		0	4
Held-to-maturity securities, Losses reclassified (from) to other comprehensive income	1		1		1	2
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Held-to-maturity Securities, Tax		1		0
Net Unrealized Losses on Retirement Plans | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Amortization of actuarial losses, net of related taxes of ($8) and net of related tax benefits of $3, respectively	12		5		17	10
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net (Gain) Loss, Tax		3		3
Foreign Currency Translation | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	$ 0		$ (1)		$ 0	$ 1