Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax				$ 2
Foreign currency translation adjustment	$ (6)	$ (3)	$ (11)	(3)
Unrealized net gains (losses) on hedges arising during the period, Before Tax Amount	185	(32)	296	46
Less: Reclassification adjustment for net (gains) losses on hedges included in interest income for loans and interest expense on long-term debt, Before Tax Amount	(48)	(34)	(122)	(86)
Net change, Before Tax Amount	137	(66)	174	(40)
Unrealized holding gains (losses) arising during the period on securities available for sale, Before Tax Amount	79	10	112	282
Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net, Before Tax Amount	(6)	(13)	(14)	(16)
Less: accretion of fair value adjustment on securities available for sale, Before Tax Amount	(1)	(35)	(4)	(59)
Less: amortization of net unrealized (gains) losses on held to maturity securities, Before Tax Amount	5	4	15	14
Net change, Before Tax Amount	77	(34)	109	221
Foreign currency translation adjustment, Before Tax Amount	(10)	(6)	(19)	(6)
Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	(6)	(6)	(19)	(10)
Recognized net actuarial (gain) loss, Before Tax Amount	35	16	91	45
Net change, Before Tax Amount	29	10	72	31
Net change in accumulated other comprehensive loss, Before Tax Amount	233	(96)	336	206
Unrealized net gains (losses) on hedges arising during the period, Tax Effect	(72)	13	(116)	(18)
Less: Reclassification adjustment for net (gains) losses on hedges included in interest income for loans and interest expense on long-term debt, Tax Effect	19	13	48	34
Net change, Tax Effect	(53)	26	(68)	16
Unrealized holding gains (losses) arising during the period on securities available for sale, Tax Effect	(31)	(4)	(44)	(111)
Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net, Tax Effect	2	5	5	6
Less: accretion of fair value adjustment on securities available for sale, Tax Effect	1	13	2	23
Less: amortization of net unrealized (gains) losses on held to maturity securities, Tax Effect	(2)	(2)	(6)	(6)
Net change, Tax Effect	(30)	12	(43)	(88)
Foreign currency translation adjustment, Tax Effect	4	3	8	3
Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), Tax	2	2	7	4
Recognized net actuarial (gain) loss, Tax Effect	(15)	(5)	(36)	(18)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax	20	11	55	27
Net change, Tax Effect	(13)	(3)	(29)	(12)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax				2
Net change in accumulated other comprehensive loss, Tax Effect	(92)	38	(132)	(81)
Unrealized net gains (losses) on hedges arising during the period, Net of Tax	113	(19)	180	28
Less: Reclassification adjustment for net (gains) losses on hedges included in interest income for loans and interest expense on long-term debt, Net of Tax	(29)	(21)	(74)	(52)
Net change, Net of Tax	84	(40)	106	(24)
Unrealized holding gains (losses) arising during the period on securities available for sale, Net of Tax	48	6	68	171
Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net, Net of Tax	(4)	(8)	(9)	(10)
Less: accretion of fair value adjustment on securities available for sale, Net of Tax	0	(22)	(2)	(36)
Less: amortization of net unrealized (gains) losses on held to maturity securities, Net of Tax	3	2	9	8
Net change, Net of Tax	47	(22)	66	133
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax				(4)
Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), Net of Tax	(4)	(4)	(12)	(6)
Net change, Net of Tax	16	7	43	19
Total other comprehensive income (loss)	$ 141	$ (58)	$ 204	$ 125