Operating Segments (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2022		Sep. 30, 2021		Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		$ 3,745		$ 3,233		$ 10,335	$ 9,763
Allocated provision for credit losses		234		(324)		310	(710)
Segment net interest income after provision		3,511		3,557		10,025	10,473
Noninterest income		2,102		2,365		6,492	6,967
Amortization of intangibles		140		145		420	431
Other expense		172		91		454	475
Income before income taxes		2,000		2,127		5,650	6,024
Provision for income taxes		363		423		1,065	1,189
Net income		1,637		1,704		4,585	4,835
Identifiable assets (period end)		548,438				548,438		$ 541,241
CB&W
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		1,685		1,665		4,780	5,103
C&CB
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		1,601		1,126		3,972	3,518
IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		40		27		94	76
OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		419	[1]	415	[1]	1,489	1,066
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		3,745		3,233		10,335	9,763
Allocated provision for credit losses		234		(324)		310	(710)
Segment net interest income after provision		3,511		3,557		10,025	10,473
Noninterest income		2,102		2,365		6,492	6,967
Amortization of intangibles		140		145		420	431
Other expense		3,473		3,650		10,447	10,985
Income before income taxes		2,000		2,127		5,650	6,024
Provision for income taxes		363		423		1,065	1,189
Net income		1,637		1,704		4,585	4,835
Identifiable assets (period end)		548,438		529,884		548,438	529,884
Operating Segments | CB&W
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		2,645		2,150		7,105	6,205
Allocated provision for credit losses		283		(5)		556	91
Segment net interest income after provision		2,362		2,155		6,549	6,114
Noninterest income		882		1,028		2,723	2,874
Amortization of intangibles		76		78		228	235
Other expense		1,876		1,907		5,584	5,628
Income before income taxes		1,292		1,198		3,460	3,125
Provision for income taxes		306		265		825	736
Net income		986		933		2,635	2,389
Identifiable assets (period end)		170,111		160,803		170,111	160,803
Operating Segments | C&CB
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		1,623		1,284		4,235	3,864
Allocated provision for credit losses		(50)		(264)		(228)	(698)
Segment net interest income after provision		1,673		1,548		4,463	4,562
Noninterest income		604		752		1,859	2,251
Amortization of intangibles		32		37		97	112
Other expense		763		767		2,236	2,277
Income before income taxes		1,482		1,496		3,989	4,424
Provision for income taxes		318		315		863	954
Net income		1,164		1,181		3,126	3,470
Identifiable assets (period end)		197,869		177,751		197,869	177,751
Operating Segments | IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		33		28		85	77
Allocated provision for credit losses		1		1		2	1
Segment net interest income after provision		32		27		83	76
Noninterest income		734		652		2,304	1,984
Amortization of intangibles		31		30		94	81
Other expense		609		507		1,729	1,451
Income before income taxes		126		142		564	528
Provision for income taxes		31		31		139	124
Net income		95		111		425	404
Identifiable assets (period end)		11,533		9,454		11,533	9,454
Operating Segments | OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income	[1]	(556)		(229)		(1,090)	(383)
Allocated provision for credit losses		0	[1]	(56)	[1]	(20)	(104)
Segment net interest income after provision	[1]	(556)		(173)		(1,070)	(279)
Noninterest income		(118)	[1]	(67)	[1]	(394)	(142)
Amortization of intangibles		1		0		1	3
Other expense		225	[1]	469	[1]	898	1,629
Income before income taxes	[1]	(900)		(709)		(2,363)	(2,053)
Provision for income taxes		(292)	[1]	(188)	[1]	(762)	(625)
Net income	[1]	(608)		(521)		(1,601)	(1,428)
Identifiable assets (period end)	[1]	168,925		181,876		168,925	181,876
Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		0		0		0	0
Intersegment Eliminations | CB&W
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		960		485		2,325	1,102
Intersegment Eliminations | C&CB
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		22		158		263	346
Intersegment Eliminations | IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		(7)		1		(9)	1
Intersegment Eliminations | OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		$ (975)	[1]	$ (644)	[1]	$ (2,579)	$ (1,449)

[1] Includes financial data from business units below the quantitative and qualitative thresholds requiring disclosure.