- Change in Each Component of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018		Jun. 30, 2019	Jun. 30, 2018
Change in accumulated other comprehensive loss balances:
Unrealized net gains (losses) on hedges arising during the period, before tax	$ 55		$ (19)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	14		(5)
Unrealized net gains (losses) on hedges arising during the period, net of tax	41		(14)		$ 51	$ (72)
Reclassification adjustment for net (gains) losses on hedges included in interest income for loans and interest expense on long-term debt, net of tax	15		6		29	6
Net change, before tax	76		(11)		109	(90)
Net change, tax	(20)		3		(29)	24
Net change, net of tax	56		(8)		80	(66)
Unrealized holding gains (losses) arising during the period on securities available for sale, net of tax	157		(45)		305	(238)
Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net, net of tax	(16)		(2)		(17)	(2)
Amortization of net unrealized (gains) losses on held to maturity securities, net of tax	5		6		10	9
Net change, before tax	198		(55)		404	(313)
Net change, tax	(52)		14		(106)	82
Net change, net of tax	146		(41)		298	(231)
Foreign currency translation adjustment, net of tax	0				0	(2)
Amortization of prior service credit, net of tax	(8)	[1]	(7)	[1]	(15)	(15)
Recognized net actuarial (gain) loss, net of tax	14	[1]	17	[1]	27	35
Net change, before tax	9		13		17	27
Net change, tax	(3)		(3)		(5)	(7)
Net change, net of tax	6		10		12	20
Other, before tax	(1)				1	(1)
Other, tax	1				0	0
Other, net of tax	0		0		1	(1)
Other Comprehensive Income (Loss), before Tax	282		(53)		531	(380)
Other Comprehensive Income (Loss), Tax	(74)		14		(140)	100
Other Comprehensive Income (Loss), Net of Tax	208		(39)		391	(280)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	(21)		(8)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	(6)		(2)
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax	214		(60)
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax	57		(15)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	22		3
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	6		1
Other Comprehensive Income Amortization of Net Unrealized Losses on Held To Maturity Securities Before Tax	(6)		(8)
Other Comprehensive Income Amortization of Net Unrealized Losses on Held To Maturity Securities Tax	(1)		(2)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax	0				0	(3)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	0				0	1
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	(10)		(11)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax	(2)		(4)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	(19)		(24)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax	$ (5)		$ (7)
Net Unrealized Gains (Losses) on Cash Flow Hedges
Change in accumulated other comprehensive loss balances:
Other Comprehensive Income (Loss), before Reclassifications, before Tax					69	(98)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax					40	8
Reclassification from AOCI, Current Period, Tax					(11)	(2)
Other Comprehensive Income (Loss) before Reclassifications, Tax					(18)	26
Accumulated Net Investment Gain (Loss) Arising During the Period, Attributable to Parent [Member]
Change in accumulated other comprehensive loss balances:
Other Comprehensive Income (Loss), before Reclassifications, before Tax					414	(322)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax					(23)	(3)
Reclassification from AOCI, Current Period, Tax					6	1
Other Comprehensive Income (Loss) before Reclassifications, Tax					(109)	84
Accumulated Net Investment Gain (Loss), Held to Maturity Securities, Attributable to Parent [Member]
Change in accumulated other comprehensive loss balances:
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax					13	12
Reclassification from AOCI, Current Period, Tax					(3)	(3)
Foreign Currency Translation Adjustment
Change in accumulated other comprehensive loss balances:
Other Comprehensive Income (Loss), Net of Tax					0
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Change in accumulated other comprehensive loss balances:
Other Comprehensive Income (Loss), before Reclassifications, before Tax					(20)	(21)
Other Comprehensive Income (Loss) before Reclassifications, Tax					5	6
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Change in accumulated other comprehensive loss balances:
Other Comprehensive Income (Loss), before Reclassifications, before Tax					37	48
Other Comprehensive Income (Loss) before Reclassifications, Tax					$ (10)	$ (13)

[1] (Dollars in millions) BeforeTaxAmount TaxEffect Net ofTaxFor the Three Months Ended June 30, 2018 Cash flow hedge activities: Unrealized net gains (losses) on hedges arising during the period $(19) $5 $(14)Reclassification adjustment for net (gains) losses on hedges included in interest income for loans and interest expense on long-term debt 8 (2) 6Net change (11) 3 (8)Securities: Unrealized holding gains (losses) arising during the period on securities available for sale (60) 15 (45)Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net (3) 1 (2)Amortization of net unrealized (gains) losses on held to maturity securities 8 (2) 6Net change (55) 14 (41)Pension and other benefits: Amortization of prior service credit(1) (11) 4 (7) Recognized net actuarial (gain) loss(1) 24 (7) 17Net change 13 (3) 10Net change in AOCI $(53) $14 $(39)