Loans and Allowance for Credit Losses - Activity in Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 7,862	$ 7,934	$ 7,925	$ 7,839
Provision for credit losses	571	557	1,609	1,678
Loans charged-off	669	669	2,042	1,916
Less recoveries of loans charged-off	(133)	(105)	(405)	(326)
Net loan charge-offs (recoveries)	536	564	1,637	1,590
Balance at end of period	7,897	7,927	7,897	7,927
Add
Provision for credit losses	571	557	1,609	1,678
Deduct
Loans charged-off	669	669	2,042	1,916
Less recoveries of loans charged-off	(133)	(105)	(405)	(326)
Net loan charge-offs (recoveries)	536	564	1,637	1,590
Commercial | Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	2,239	2,180	2,175	2,119
Provision for credit losses	111	155	466	475
Loans charged-off	129	165	471	484
Less recoveries of loans charged-off	(37)	(18)	(88)	(78)
Net loan charge-offs (recoveries)	92	147	383	406
Balance at end of period	2,258	2,188	2,258	2,188
Add
Provision for credit losses	111	155	466	475
Deduct
Loans charged-off	129	165	471	484
Less recoveries of loans charged-off	(37)	(18)	(88)	(78)
Net loan charge-offs (recoveries)	92	147	383	406
Commercial | Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	1,384	1,596	1,508	1,620
Provision for credit losses	46	49	(25)	82
Loans charged-off	110	80	209	152
Less recoveries of loans charged-off	(7)	(10)	(53)	(25)
Net loan charge-offs (recoveries)	103	70	156	127
Balance at end of period	1,327	1,575	1,327	1,575
Add
Provision for credit losses	46	49	(25)	82
Deduct
Loans charged-off	110	80	209	152
Less recoveries of loans charged-off	(7)	(10)	(53)	(25)
Net loan charge-offs (recoveries)	103	70	156	127
Consumer | Residential mortgages
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	757	836	783	827
Provision for credit losses	28	(36)	1	(31)
Loans charged-off	3	3	11	10
Less recoveries of loans charged-off	(4)	(6)	(13)	(17)
Net loan charge-offs (recoveries)	(1)	(3)	(2)	(7)
Balance at end of period	786	803	786	803
Add
Provision for credit losses	28	(36)	1	(31)
Deduct
Loans charged-off	3	3	11	10
Less recoveries of loans charged-off	(4)	(6)	(13)	(17)
Net loan charge-offs (recoveries)	(1)	(3)	(2)	(7)
Consumer | Credit card
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	2,665	2,498	2,640	2,403
Provision for credit losses	311	349	978	1,055
Loans charged-off	344	347	1,103	1,042
Less recoveries of loans charged-off	(60)	(48)	(177)	(132)
Net loan charge-offs (recoveries)	284	299	926	910
Balance at end of period	2,692	2,548	2,692	2,548
Add
Provision for credit losses	311	349	978	1,055
Deduct
Loans charged-off	344	347	1,103	1,042
Less recoveries of loans charged-off	(60)	(48)	(177)	(132)
Net loan charge-offs (recoveries)	284	299	926	910
Consumer | Other retail
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	817	824	819	870
Provision for credit losses	75	40	189	97
Loans charged-off	83	74	248	228
Less recoveries of loans charged-off	(25)	(23)	(74)	(74)
Net loan charge-offs (recoveries)	58	51	174	154
Balance at end of period	834	813	834	813
Add
Provision for credit losses	75	40	189	97
Deduct
Loans charged-off	83	74	248	228
Less recoveries of loans charged-off	(25)	(23)	(74)	(74)
Net loan charge-offs (recoveries)	$ 58	$ 51	$ 174	$ 154