Shareholders' Equity (Adjustments to Accumulated Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Class of Stock [Line Items]
Net interest revenue	$ 570	$ 546	$ 1,686	$ 1,718
Net gains (losses) from sales of available-for-sale securities			(15)	(11)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(591)	326	(518)	23
Total reclassifications out of AOCI	542	531	1,500	1,557
Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Total reclassifications out of AOCI	3	2	13	18
Net Unrealized Gains (Losses) on Cash Flow Hedges | Interest-rate contracts | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	0	0	1	1
Net interest revenue	1	0	2	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	0	(4)	(9)	(7)
Gain (Loss) on Investments, Excluding Other than Temporary Impairments, Tax	0	(2)	(6)	(4)
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
Held-to-maturity securities, Losses reclassified (from) to other comprehensive income	0	1	1	3
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income Loss, Tax, Including Portion Attributable to Noncontrolling Interest, Available-for-sale Securities	0	1	0	2
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Held-to-maturity Securities, Tax	0	0	0	3
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 tax benefits of $3 and $3, respectively	2	5	19	15
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net (Gain) Loss, Tax	3	3	(2)	9
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
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Tax	$ 0	$ 0	$ 0	$ (1)