Operating Segments (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2022		Jun. 30, 2021		Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		$ 3,407		$ 3,245		$ 6,590	$ 6,530
Allocated provision for credit losses		171		(434)		76	(386)
Segment net interest income after provision		3,236		3,679		6,514	6,916
Noninterest income		2,248		2,405		4,390	4,602
Amortization of intangibles		143		142		280	286
Other expense		144		275		282	384
Income before income taxes		1,904		2,073		3,650	3,897
Provision for income taxes		372		415		702	766
Net income		1,532		1,658		2,948	3,131
Identifiable assets (period end)		545,123				545,123		$ 541,241
CB&W
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		1,567		1,687		3,095	3,440
C&CB
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		1,277		1,182		2,371	2,391
IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		30		25		54	49
OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		533	[1]	351	[1]	1,070	650
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		3,407		3,245		6,590	6,530
Allocated provision for credit losses		171		(434)		76	(386)
Segment net interest income after provision		3,236		3,679		6,514	6,916
Noninterest income		2,248		2,405		4,390	4,602
Amortization of intangibles		143		142		280	286
Other expense		3,437		3,869		6,974	7,335
Income before income taxes		1,904		2,073		3,650	3,897
Provision for income taxes		372		415		702	766
Net income		1,532		1,658		2,948	3,131
Identifiable assets (period end)		545,123		521,964		545,123	521,964
Operating Segments | CB&W
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		2,274		2,072		4,456	4,056
Allocated provision for credit losses		199		(4)		272	96
Segment net interest income after provision		2,075		2,076		4,184	3,960
Noninterest income		892		925		1,842	1,845
Amortization of intangibles		79		78		152	157
Other expense		1,875		1,867		3,710	3,721
Income before income taxes		1,013		1,056		2,164	1,927
Provision for income taxes		240		257		518	471
Net income		773		799		1,646	1,456
Identifiable assets (period end)		166,378		156,520		166,378	156,520
Operating Segments | C&CB
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		1,334		1,296		2,604	2,578
Allocated provision for credit losses		(28)		(399)		(178)	(434)
Segment net interest income after provision		1,362		1,695		2,782	3,012
Noninterest income		636		808		1,255	1,500
Amortization of intangibles		32		38		65	75
Other expense		749		790		1,472	1,513
Income before income taxes		1,217		1,675		2,500	2,924
Provision for income taxes		263		369		543	639
Net income		954		1,306		1,957	2,285
Identifiable assets (period end)		193,406		178,746		193,406	178,746
Operating Segments | IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		28		25		52	49
Allocated provision for credit losses		1		(1)		1	0
Segment net interest income after provision		27		26		51	49
Noninterest income		833		698		1,571	1,332
Amortization of intangibles		32		24		63	51
Other expense		592		491		1,121	944
Income before income taxes		236		209		438	386
Provision for income taxes		58		50		108	94
Net income		178		159		330	292
Identifiable assets (period end)		11,126		8,649		11,126	8,649
Operating Segments | OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income	[1]	(229)		(148)		(522)	(153)
Allocated provision for credit losses		(1)	[1]	(30)	[1]	(19)	(48)
Segment net interest income after provision	[1]	(228)		(118)		(503)	(105)
Noninterest income		(113)	[1]	(26)	[1]	(278)	(75)
Amortization of intangibles		0		2		0	3
Other expense		221	[1]	721	[1]	671	1,157
Income before income taxes	[1]	(562)		(867)		(1,452)	(1,340)
Provision for income taxes		(189)	[1]	(261)	[1]	(467)	(438)
Net income	[1]	(373)		(606)		(985)	(902)
Identifiable assets (period end)	[1]	174,213		178,049		174,213	178,049
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		707		385		1,361	616
Intersegment Eliminations | C&CB
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		57		114		233	187
Intersegment Eliminations | IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		(2)		0		(2)	0
Intersegment Eliminations | OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		$ (762)	[1]	$ (499)	[1]	$ (1,592)	$ (803)

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