Operating Segments (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		$ 3,625	$ 3,407	$ 7,493	$ 6,590
Allocated provision for credit losses		538	171	1,040	76
Segment net interest income after provision		3,087	3,236	6,453	6,514
Noninterest income		2,293	2,248	4,527	4,390
Amortization of intangibles		131	143	267	280
Other expense		250	152	541	334
Income before income taxes		1,632	1,904	3,541	3,650
Provision for income taxes		287	372	681	702
Net income		1,345	1,532	2,860	2,948
Identifiable assets (period end)		554,549		554,549		$ 555,255
CB&W
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		1,454	1,568	3,057	3,095
C&CB
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		2,420	1,305	4,726	2,424
IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		1	1	2	1
Provision for income taxes		54
OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income	[1]	(250)	533	(292)	1,070
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		3,625	3,407	7,493	6,590
Allocated provision for credit losses		538	171	1,040	76
Segment net interest income after provision		3,087	3,236	6,453	6,514
Noninterest income		2,293	2,248	4,527	4,390
Amortization of intangibles		131	143	267	280
Other expense		3,617	3,437	7,172	6,974
Income before income taxes		1,632	1,904	3,541	3,650
Provision for income taxes		287	372	681	702
Net income		1,345	1,532	2,860	2,948
Identifiable assets (period end)		554,549	545,123	554,549	545,123
Operating Segments | CB&W
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		2,668	2,293	5,416	4,482
Allocated provision for credit losses		224	199	498	272
Segment net interest income after provision		2,444	2,094	4,918	4,210
Noninterest income		828	831	1,701	1,742
Amortization of intangibles		68	79	137	153
Other expense		1,980	1,848	3,968	3,661
Income before income taxes		1,224	998	2,514	2,138
Provision for income taxes		293	238	601	512
Net income		931	760	1,913	1,626
Identifiable assets (period end)		163,940	165,962	163,940	165,962
Operating Segments | C&CB
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		1,700	1,359	3,447	2,644
Allocated provision for credit losses		312	(27)	544	(177)
Segment net interest income after provision		1,388	1,386	2,903	2,821
Noninterest income		576	688	1,206	1,344
Amortization of intangibles		31	33	62	66
Other expense		841	782	1,693	1,538
Income before income taxes		1,092	1,259	2,354	2,561
Provision for income taxes		212	273	474	555
Net income		880	986	1,880	2,006
Identifiable assets (period end)		209,824	197,672	209,824	197,672
Operating Segments | IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		(84)	6	(70)	8
Allocated provision for credit losses		0	0	0	0
Segment net interest income after provision		(84)	6	(70)	8
Noninterest income		944	830	1,761	1,563
Amortization of intangibles		32	31	68	61
Other expense		673	579	1,323	1,095
Income before income taxes		155	226	300	415
Provision for income taxes		0	55	36	102
Net income		155	171	264	313
Identifiable assets (period end)		9,500	7,090	9,500	7,090
Operating Segments | OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income	[1]	(659)	(251)	(1,300)	(544)
Allocated provision for credit losses	[1]	2	(1)	(2)	(19)
Segment net interest income after provision	[1]	(661)	(250)	(1,298)	(525)
Noninterest income	[1]	(55)	(101)	(141)	(259)
Amortization of intangibles	[1]	0	0	0	0
Other expense	[1]	123	228	188	680
Income before income taxes	[1]	(839)	(579)	(1,627)	(1,464)
Provision for income taxes	[1]	(218)	(194)	(430)	(467)
Net income	[1]	(621)	(385)	(1,197)	(997)
Identifiable assets (period end)	[1]	171,285	174,399	171,285	174,399
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		1,214	725	2,359	1,387
Intersegment Eliminations | C&CB
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		(720)	54	(1,279)	220
Intersegment Eliminations | IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income		(85)	5	(72)	7
Intersegment Eliminations | OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net Interest Income	[1]	$ (409)	$ (784)	$ (1,008)	$ (1,614)

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