Business Segment Information - Schedule of Disaggregation of Noninterest Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Personnel expense	$ 1,137	$ 1,100	$ 1,101
Net occupancy expense	130	123	128
Computer software	121	111	113
Operations services	94	87	87
Deposit insurance expense	64	122	32
Legal and professional fees	64	49	62
Contract employment and outsourcing	51	49	54
Advertising and public relations	48	71	50
Amortization of intangible assets	44	47	51
Equipment expense	42	42	45
Communications and delivery	32	35	37
Contributions	18	61	7
Other expense	190	182	186
Cost allocations	0	0	0
Total noninterest expense	2,035	2,079	1,953
Commercial, Consumer & Wealth
Disaggregation of Revenue [Line Items]
Personnel expense	540	526	516
Net occupancy expense	76	72	72
Computer software	25	21	27
Operations services	18	20	21
Deposit insurance expense	0	0	0
Legal and professional fees	11	10	11
Contract employment and outsourcing	5	6	6
Advertising and public relations	7	7	6
Amortization of intangible assets	39	43	46
Equipment expense	11	13	14
Communications and delivery	10	10	9
Contributions	2	2	2
Other expense	75	71	68
Cost allocations	598	569	511
Total noninterest expense	1,417	1,370	1,309
Wholesale
Disaggregation of Revenue [Line Items]
Personnel expense	196	179	240
Net occupancy expense	9	9	11
Computer software	6	5	4
Operations services	22	25	22
Deposit insurance expense	0	0	0
Legal and professional fees	3	3	3
Contract employment and outsourcing	3	4	5
Advertising and public relations	1	1	1
Amortization of intangible assets	2	1	2
Equipment expense	2	1	1
Communications and delivery	3	5	6
Contributions	0	0	0
Other expense	22	20	29
Cost allocations	30	23	20
Total noninterest expense	299	276	344
Corporate
Disaggregation of Revenue [Line Items]
Personnel expense	401	395	345
Net occupancy expense	45	42	45
Computer software	90	85	82
Operations services	54	42	44
Deposit insurance expense	64	122	32
Legal and professional fees	50	36	48
Contract employment and outsourcing	43	39	43
Advertising and public relations	40	63	43
Amortization of intangible assets	3	3	3
Equipment expense	29	28	30
Communications and delivery	19	20	22
Contributions	16	59	5
Other expense	93	91	89
Cost allocations	(628)	(592)	(531)
Total noninterest expense	$ 319	$ 433	$ 300