Loans and ACL - Allowance for Credit Losses (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses		$ 777	$ (813)	$ 2,335
Commercial: | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1,426	2,204	570
Charge-Offs		(143)	(243)	(412)
Recoveries		87	107	96
Provision for credit losses		39	(642)	952
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	0	998
Ending balance		1,409	1,426	2,204
Commercial: | CRE
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		350	573	150
Charge-Offs		(13)	(10)	(78)
Recoveries		8	6	5
Provision for credit losses		(121)	(219)	414
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	0	82
Ending balance		224	350	573
Commercial: | Commercial construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		52	81	52
Charge-Offs		(1)	(2)	(30)
Recoveries		5	4	11
Provision for credit losses		(10)	(31)	32
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	0	16
Ending balance		46	52	81
Consumer: | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		308	368	176
Charge-Offs		(9)	(23)	(56)
Recoveries		16	12	10
Provision for credit losses		84	(49)	(27)
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	0	265
Ending balance		399	308	368
Consumer: | Residential home equity and direct
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		615	714	107
Charge-Offs		(294)	(214)	(231)
Recoveries		81	79	66
Provision for credit losses		147	36	318
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	0	454
Ending balance		549	615	714
Consumer: | Indirect auto
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1,022	1,198	304
Charge-Offs		(411)	(336)	(378)
Recoveries		91	92	87
Provision for credit losses		279	68	367
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	0	818
Ending balance		981	1,022	1,198
Consumer: | Indirect other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		195	208	60
Charge-Offs		(100)	(57)	(60)
Recoveries		23	24	23
Provision for credit losses		193	20	35
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	0	150
Ending balance		311	195	208
Consumer: | Student
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		117	130	0
Charge-Offs		(22)	(24)	(23)
Recoveries		1	1	1
Provision for credit losses		2	4	23
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	6	129
Ending balance		98	117	130
Credit card
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		350	359	122
Charge-Offs		(176)	(150)	(182)
Recoveries		34	37	32
Provision for credit losses		152	104	212
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	0	175
Ending balance		360	350	359
ALLL
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		4,435	5,835	1,549
Charge-Offs		(1,169)	(1,059)	(1,450)
Recoveries		346	362	331
Provision for credit losses		765	(709)	2,326
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	6	3,079
Ending balance		4,377	4,435	5,835
RUFC
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		260	364	340
Charge-Offs		0	0	0
Recoveries		0	0	0
Provision for credit losses		12	(104)	9
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	0	15
Ending balance		272	260	364
ACL
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		4,695	6,199	1,889
Charge-Offs		(1,169)	(1,059)	(1,450)
Recoveries		346	362	331
Provision for credit losses		777	(813)	2,335
Allowance for Loan and Lease Losses, Adjustments, Other	[1]	0	6	3,094
Ending balance		$ 4,649	4,695	6,199
PCI
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance			$ 0	8
Charge-Offs				0
Recoveries				0
Provision for credit losses				0
Allowance for Loan and Lease Losses, Adjustments, Other	[1]			(8)
Ending balance				$ 0

[1] Includes the amounts for the ALLL for PCD acquisitions, and other activity.