Loans and Related Allowance for Credit Losses (Rollforward of Allowance for Credit Losses of Loans and Leases) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 4,486	$ 4,791	$ 4,791
Charge-offs	(312)	(330)
Recoveries	107	87
Net (charge-offs)	(205)	(243)
Provision for credit losses	260	147
Other	3	(2)
Ending balance	4,544	4,693	4,486
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	719	663	663
Provision for (recapture of) credit losses	(46)	9
Other	1	0
Ending balance	674	672	719
Allowance for credit loss	5,218	5,365	5,200
Allowances for investment securities and other financial assets	91	117
Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3,148	3,259	3,259
Charge-offs	(131)	(148)	(720)
Recoveries	47	23
Net (charge-offs)	(84)	(125)
Provision for credit losses	138	85
Other	3	(2)
Ending balance	3,205	3,217	3,148
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	580	545	545
Provision for (recapture of) credit losses	(53)	(17)
Other	1	0
Ending balance	528	528	580
Allowance for credit loss	3,733	3,745
Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,338	1,532	1,532
Charge-offs	(181)	(182)
Recoveries	60	64
Net (charge-offs)	(121)	(118)
Provision for credit losses	122	62
Other	0	0
Ending balance	1,339	1,476	1,338
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	139	118	118
Provision for (recapture of) credit losses	7	26
Other	0	0
Ending balance	146	144	$ 139
Allowance for credit loss	$ 1,485	$ 1,620