- Change in Each Component of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020	Jun. 30, 2019
Change in accumulated other comprehensive loss balances:
Unrealized net gains (losses) on hedges arising during the period, before tax	$ 54		$ 55
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	14		14
Unrealized net gains (losses) on hedges arising during the period, net of tax	40		41		$ 352	$ 51
Reclassification adjustment for net (gains) losses on hedges included in interest income for loans and interest expense on long-term debt, net of tax	(6)		15		8	29
Net change, before tax	46		76		488	109
Net change, tax	(12)		(20)		(128)	(29)
Net change, net of tax	34		56		360	80
Unrealized holding gains (losses) arising during the period on securities available for sale, net of tax	214		157		506	305
Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net, net of tax	(42)		(16)		(81)	(17)
Amortization of net unrealized (gains) losses on held to maturity securities, net of tax	7		5		12	10
Net change, before tax	242		198		592	404
Net change, tax	(63)		(52)		(155)	(106)
Net change, net of tax	179		146		437	298
Amortization of prior service credit, net of tax	(5)	[1]	(8)	[1]	(10)	(15)
Recognized net actuarial (gain) loss, net of tax	20	[1]	14	[1]	41	27
Net change, before tax	21		9		42	17
Net change, tax	(6)		(3)		(11)	(5)
Net change, net of tax	15		6		31	12
Other, before tax			(1)			1
Other, tax			1			0
Other Comprehensive Income, Other, Net of Tax						1
Other, net of tax	0		0		0	1
Other Comprehensive Income (Loss), before Tax	309		282		1,122	531
Other Comprehensive Income (Loss), Tax	(81)		(74)		(294)	(140)
Other Comprehensive Income (Loss), Net of Tax	228		208		828	391
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	8		(21)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	2		(6)
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, before Tax	290		214
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax	76		57
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	57		22
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	15		6
Other Comprehensive Income Amortization of Net Unrealized Losses on Held To Maturity Securities Before Tax	(9)		(6)
Other Comprehensive Income Amortization of Net Unrealized Losses on Held To Maturity Securities Tax	(2)		(1)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	(7)		(10)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax	(2)		(2)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	(28)		(19)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax	$ (8)		$ (5)
Net Unrealized Gains (Losses) on Cash Flow Hedges
Change in accumulated other comprehensive loss balances:
Other Comprehensive Income (Loss), before Reclassifications, before Tax					477	69
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax					11	40
Reclassification from AOCI, Current Period, Tax					(3)	(11)
Other Comprehensive Income (Loss) before Reclassifications, Tax					(125)	(18)
Accumulated Net Investment Gain (Loss) Arising During the Period, Attributable to Parent
Change in accumulated other comprehensive loss balances:
Other Comprehensive Income (Loss), before Reclassifications, before Tax					686	414
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax					(110)	(23)
Reclassification from AOCI, Current Period, Tax					29	6
Other Comprehensive Income (Loss) before Reclassifications, Tax					(180)	(109)
Accumulated Net Investment Gain (Loss), Held to Maturity Securities, Attributable to Parent
Change in accumulated other comprehensive loss balances:
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax					16	13
Reclassification from AOCI, Current Period, Tax					(4)	(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
Change in accumulated other comprehensive loss balances:
Other Comprehensive Income (Loss), before Reclassifications, before Tax					(14)	(20)
Other Comprehensive Income (Loss) before Reclassifications, Tax					4	5
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Change in accumulated other comprehensive loss balances:
Other Comprehensive Income (Loss), before Reclassifications, before Tax					56	37
Other Comprehensive Income (Loss) before Reclassifications, Tax					$ (15)	$ (10)

[1] (Dollars in millions) BeforeTaxAmount TaxEffect Net ofTaxFor the Three Months Ended June 30, 2019 Cash flow hedge activities: Unrealized net gains (losses) on hedges arising during the period $55 $(14) $41Reclassification adjustment for net (gains) losses on hedges included in interest income for loans and interest expense on long-term debt 21 (6) 15Net change 76 (20) 56Securities: Unrealized holding gains (losses) arising during the period on securities available for sale 214 (57) 157Reclassification adjustment for net (gains) losses on securities available for sale included in securities gains, net (22) 6 (16)Amortization of net unrealized (gains) losses on held to maturity securities 6 (1) 5Net change 198 (52) 146Pension and other benefits: Amortization of prior service credit(1) (10) 2 (8) Recognized net actuarial (gain) loss(1) 19 (5) 14Net change 9 (3) 6Other (1) 1 —Net change in AOCI $282 $(74) $208