Accumulated Other Comprehensive Loss (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
Accumulated Other Comprehensive Loss
Unrealized net gains on hedges arising during the period, Before Tax Amount	$ 30	$ 39	$ 39	$ 77
Less: Reclassification adjustment for net losses on hedges included in net income, Before Tax Amount	(13)	(5)	(27)	(10)
Net change in unrealized gains (losses) on hedges, Before Tax Amount	17	34	12	67
Unrealized holding gains arising during the period on securities available for sale, Before Tax Amount	145	42	(358)	189
Reclassification adjustment for net gains on securities available for sale included in net income, Before Tax Amount	(47)	(41)	(170)	(88)
Reclassification of unrealized loss on held to maturity securities transferred to securities available for sale, Before Tax Amount		301		301
Less: accretion of fair value adjustment on securities available for sale, Before Tax Amount	(31)	(1)	(69)	(2)
Less: accretion of fair value adjustment on held to maturity securities, Before Tax Amount	(1)	(9)	(12)	(23)
Less: amortization of net unrealized losses on held to maturity securities, Before Tax Amount	(156)	28	(131)	84
Net change in unrealized losses on securities, before Tax Amount	(90)	320	(740)	461
Foreign currency translation adjustment, Before Tax Amount	1	3	(4)	2
Amortization of transition amount, Before Tax Amount		1		1
Recognized net actuarial loss, Before Tax Amount	29	25	87	74
Net change in pension and other benefits, Before Tax Amount	29	26	87	75
Net change in accumulated other comprehensive loss, Before Tax Amount	(43)	383	(645)	605
Unrealized net gains on hedges arising during the period, Tax Effect	(12)	(15)	(15)	(30)
Less: Reclassification adjustment for net losses on hedges included in net income, Tax Effect	6	2	11	4
Net change in unrealized losses on hedges, Tax Effect	(6)	(13)	(4)	(26)
Unrealized holding gains arising during the period on securities available for sale, Tax Effect	(56)	(16)	141	(74)
Reclassification adjustment for net gains on securities available for sale included in net income, Tax Effect	18	17	67	35
Reclassification of unrealized loss on held to maturity securities transferred to securities available for sale, Tax Effect		(118)		(118)
Less: accretion of fair value adjustment on securities available for sale, Tax Effect	11		27	1
Less: accretion of fair value adjustment on held to maturity securities, Tax Effect	1	3	5	9
Less: amortization of net unrealized losses on held to maturity securities, Tax Effect	61	(11)	51	(33)
Net change in unrealized losses on securities, Tax Effect	35	(125)	291	(180)
Foreign currency translation adjustment, Tax Effect	(1)	(2)	1	(1)
Recognized net actuarial loss, Tax Effect	(11)	(10)	(34)	(29)
Net change in pension and other benefits, Tax Effect	(11)	(10)	(34)	(29)
Net change in accumulated other comprehensive loss, Tax Effect	17	(150)	254	(236)
Unrealized net gains on hedges arising during the period, Net of Tax	18	24	24	47
Less: Reclassification adjustment for net losses on hedges included in net income, Net of Tax	(7)	(3)	(16)	(6)
Net change in unrealized gains (losses) on hedges, Net of Tax	11	21	8	41
Unrealized holding gains arising during the period on securities available for sale, Net of Tax	89	26	(217)	115
Reclassification adjustment for net gains on securities available for sale included in net income, Net of Tax	(29)	(24)	(103)	(53)
Reclassification of unrealized loss on held to maturity securities transferred to securities available for sale, Net of Tax		183		183
Less: accretion of fair value adjustment on securities available for sale, Net of Tax	(20)	(1)	(42)	(1)
Less: accretion of fair value adjustment on held to maturity securities, Net of Tax		(6)	(7)	(14)
Less: amortization of net unrealized losses on held to maturity securities, Net of Tax	(95)	17	(80)	51
Net change in unrealized losses on securities, Net of Tax	(55)	195	(449)	281
Foreign currency translation adjustment, Net of Tax		1	(3)	1
Amortization of transition amount, Net of Tax		1		1
Recognized net actuarial loss, Net of Tax	18	15	53	45
Net change in pension and other benefits, Net of Tax	18	16	53	46
Net change in accumulated other comprehensive loss, Net of Tax	$ (26)	$ 233	$ (391)	$ 369