Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized net gains (losses) on hedges arising during the period, Before Tax Amount	$ 144	$ (8)	$ 410	$ 111
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	(44)	(41)	(87)	(74)
Net change, Before Tax Amount	100	(49)	323	37
Unrealized holding gains (losses) arising during the period on securities available for sale, Before Tax Amount	105	(87)	263	33
Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net, Before Tax Amount	(19)	(5)	(32)	(8)
Less: accretion of fair value adjustment on securities available for sale, Before Tax Amount		(1)		(3)
Less: amortization of net unrealized (gains) losses on held to maturity securities, Before Tax Amount	5	5	10	10
Net change, Before Tax Amount	91	(88)	241	32
Foreign currency translation adjustment, Before Tax Amount	1	3	8	(9)
Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	(7)	(7)	(13)	(13)
Net change, Before Tax Amount	15	20	31	43
Other Comprehensive Income Other Before Tax	2
Net change in accumulated other comprehensive loss, Before Tax Amount	209	(114)	603	103
Unrealized net gains (losses) on hedges arising during the period, Tax Effect	(56)	3	(161)	(44)
Less: Reclassification adjustment for net (gains) losses on hedges included in interest income for loans and interest expense on long-term debt, Tax Effect	17	16	34	29
Net change, Tax Effect	(39)	19	(127)	(15)
Net change in unrealized gains (losses) on cash flow hedges	61	(30)	196	22
Unrealized holding gains (losses) arising during the period on securities available for sale, Tax Effect	(41)	34	(103)	(13)
Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net, Tax Effect	7	2	12	3
Less: accretion of fair value adjustment on securities available for sale, Tax Effect		0		1
Less: amortization of net unrealized (gains) losses on held to maturity securities, Tax Effect	(2)	(2)	(4)	(4)
Net change, Tax Effect	(36)	34	(95)	(13)
Net change in unrealized gains (losses) on investment securities	55	(54)	146	19
Foreign currency translation adjustment, Tax Effect	0	(1)	(3)	4
Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), Tax	2	3	5	5
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	8	10	17	21
Net change, Tax Effect	(6)	(7)	(12)	(16)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	(9)	(13)	(19)	(27)
Other Comprehensive Income Other Tax	(1)
Net change in accumulated other comprehensive loss, Tax Effect	(82)	45	(237)	(40)
Unrealized net gains (losses) on hedges arising during the period, Net of Tax	88	(5)	249	67
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	(27)	(25)	(53)	(45)
Net change, Net of Tax	61	(30)		22
Unrealized holding gains (losses) arising during the period on securities available for sale, Net of Tax	64	(53)	160	20
Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net, Net of Tax	(12)	(3)	(20)	(5)
Less: accretion of fair value adjustment on securities available for sale, Net of Tax		(1)		(2)
Less: amortization of net unrealized (gains) losses on held to maturity securities, Net of Tax	3	3	6	6
Net change, Net of Tax	1	2	5	(5)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	22	27	44	56
Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), Net of Tax	(5)	(4)	(8)	(8)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax	14	17	27	35
Net change, Net of Tax	9	13		27
Other Comprehensive Income, Other, Net of Tax	1	0	0	0
Total other comprehensive income (loss)	$ 127	$ (69)	366	$ 63
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss)			$ 366