Shareholders' Equity (Adjustments to Accumulated Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Class of Stock [Line Items]
Net interest revenue	$ 555	$ 576
Net gains (losses) from sales of available-for-sale securities	(15)
Total reclassifications out of AOCI	356	455
Reclassification out of Accumulated Other Comprehensive Income [Member]
Class of Stock [Line Items]
Total reclassifications out of AOCI	(3)	5
Net Unrealized Gains (Losses) on Cash Flow Hedges | Interest-rate contracts | Reclassification out of Accumulated Other Comprehensive Income [Member]
Class of Stock [Line Items]
Net interest revenue	1	1
Net Unrealized Gains (Losses) on Available-for-Sale Securities | Reclassification out of Accumulated Other Comprehensive Income [Member]
Class of Stock [Line Items]
Net gains (losses) from sales of available-for-sale securities	(9)	(3)
Net realized gain from sales of available-for-sale securities, tax	(6)	(2)
Other-Than-Temporary Impairment on Held-to-Maturity Securities | Reclassification out of Accumulated Other Comprehensive Income [Member]
Class of Stock [Line Items]
Held-to-maturity securities, Losses reclassified (from) to other comprehensive income	0	2
Other-than-temporary impairment on held-to-maturity securities related to factors other than credit, tax	1	0
Net Unrealized Losses on Retirement Plans | Reclassification out of Accumulated Other Comprehensive Income [Member]
Class of Stock [Line Items]
Amortization of actuarial losses, net of related tax benefits of $3 and $3, respectively	5	5
Amortization of actuarial losses, tax	$ 3	$ 3