Business Segment Information - Schedule of Disaggregation of Noninterest Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Fixed income	$ 187	$ 133	$ 205
Deposit transactions and cash management	176	179	171
Brokerage, management fees and commissions	101	90	92
Card and digital banking fees	77	77	84
Other service charges and fees	51	54	54
Trust services and investment management	48	47	48
Mortgage banking income	35	23	68
Gain on merger termination	0	225	0
Securities gains (losses), net	(89)	(4)	18
Other income	93	103	75
Total noninterest income	679	927	815
Underwriting, Portfolio Advisory, and Other Noninterest Income
Segment Reporting Information [Line Items]
Revenue from contract with customer	42	42	43
Commercial, Consumer & Wealth
Segment Reporting Information [Line Items]
Fixed income	0	0	0
Deposit transactions and cash management	163	165	161
Brokerage, management fees and commissions	101	90	92
Card and digital banking fees	67	67	72
Other service charges and fees	48	51	49
Trust services and investment management	48	47	48
Mortgage banking income	1	1	22
Gain on merger termination		0
Securities gains (losses), net	0	0	0
Other income	33	27	33
Total noninterest income	461	448	477
Wholesale
Segment Reporting Information [Line Items]
Fixed income	187	134	205
Deposit transactions and cash management	4	4	3
Brokerage, management fees and commissions	0	0	0
Card and digital banking fees	0	0	0
Other service charges and fees	2	3	3
Trust services and investment management	0	0	0
Mortgage banking income	33	21	46
Gain on merger termination		0
Securities gains (losses), net	0	0	0
Other income	4	12	2
Total noninterest income	230	174	259
Corporate
Segment Reporting Information [Line Items]
Fixed income	0	(1)	0
Deposit transactions and cash management	9	10	7
Brokerage, management fees and commissions	0	0	0
Card and digital banking fees	10	10	12
Other service charges and fees	1	0	2
Trust services and investment management	0	0	0
Mortgage banking income	1	1	0
Gain on merger termination		225
Securities gains (losses), net	(89)	(4)	18
Other income	56	64	40
Total noninterest income	$ (12)	$ 305	$ 79