Allowance for Credit Losses - Rollforward of Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 815	$ 773	$ 685
Charge-offs	(166)	(157)	(199)
Recoveries	46	45	29
Provision for loan and lease losses	43	154	264
Ending balance	738	815	773	$ 685
Off-Balance-Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	79	83	87
Provision for unfunded lending commitments	22	(4)	(4)
Ending balance	101	79	83	$ 87
Allowance for credit losses	839	894	$ 856
Accounting Standards Update [Extensible List]			Accounting Standards Update 2023-02 [Member]	Accounting Standards Update 2022-02 [Member]
Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			$ (6)
Ending balance				$ (6)
Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	345	339	308
Charge-offs	(126)	(77)	(156)
Recoveries	32	30	14
Provision for loan and lease losses	84	53	172
Ending balance	335	345	339	308
Off-Balance-Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	57	49	55
Provision for unfunded lending commitments	24	8	(6)
Ending balance	81	57	49	55
Allowance for credit losses	416	402	388
Commercial | Commercial and industrial | Single Company
Allowance for Loan and Lease Losses [Roll Forward]
Charge-offs			(72)
Commercial | Commercial and industrial | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			1
Ending balance				1
Commercial | Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	227	172	146
Charge-offs	(15)	(56)	(17)
Recoveries	3	1	2
Provision for loan and lease losses	(38)	110	41
Ending balance	177	227	172	146
Off-Balance-Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	11	22	22
Provision for unfunded lending commitments	0	(11)	0
Ending balance	11	11	22	22
Allowance for credit losses	188	238	194
Commercial | Commercial real estate | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			0
Ending balance				0
Consumer | Consumer real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	221	233	200
Charge-offs	(5)	(3)	(4)
Recoveries	6	9	9
Provision for loan and lease losses	(16)	(18)	35
Ending balance	206	221	233	200
Off-Balance-Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	11	12	10
Provision for unfunded lending commitments	(2)	(1)	2
Ending balance	9	11	12	10
Allowance for credit losses	215	232	245
Consumer | Consumer real estate | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			(7)
Ending balance				(7)
Consumer | Credit card and other:
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	22	29	31
Charge-offs	(20)	(21)	(22)
Recoveries	5	5	4
Provision for loan and lease losses	13	9	16
Ending balance	20	22	29	31
Off-Balance-Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	0	0	0
Provision for unfunded lending commitments	0	0	0
Ending balance	0	0	0	0
Allowance for credit losses	$ 20	$ 22	29
Consumer | Credit card and other: | Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			$ 0
Ending balance				$ 0