Allowance for Credit Losses - Summary (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Allowance for Credit Losses
Beginning balance	$ 24,345	$ 22,420	$ 22,420
Gross charge-offs	8,941	7,674
Gross recoveries collected	(1,606)	(1,400)
Net charge-offs/(recoveries)	7,335	6,274
Provision for loan losses	8,720	7,798
Other	5	5
Ending balance	25,735	23,949	24,345
Allowance for lending-related commitments
Beginning balance	2,101	1,974	1,974
Provision for lending-related commitments	862	168
Other	1	0
Ending balance	2,964	2,142	2,101
Total allowance for investment securities	105	175	152
Total allowance for credit losses	28,804	26,266
Allowance for loan losses by impairment methodology
Asset-specific	217	(257)
Portfolio-based	25,518	24,206
Total allowance for loan losses	25,735	23,949	24,345
Loans by impairment methodology
Asset-specific	8,261	6,294
Portfolio-based	1,361,524	1,279,076
Total retained loans	1,369,785	1,285,370	1,299,590
Allowance for lending-related commitments by impairment methodology
Asset-specific	131	93
Portfolio-based	2,833	2,049
Total allowance for lending-related commitments	2,964	2,142	2,101
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	1,025	619
Portfolio-based	570,953	541,077
Total lending-related commitments	571,978	541,696
CIB
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Allowance for credit losses associated with accounts receivable	285	277
Collateral-dependent loans
Allowance for Credit Losses
Net charge-offs/(recoveries)	474	151
Collateral-dependent loans
Loans measured at fair value of collateral less cost to sell	5,235	4,329
Consumer, excluding credit card
Allowance for Credit Losses
Beginning balance	1,807	1,856	1,856
Gross charge-offs	814	971
Gross recoveries collected	(410)	(490)
Net charge-offs/(recoveries)	404	481
Provision for loan losses	500	360
Other	0	0
Ending balance	1,903	1,735	1,807
Allowance for lending-related commitments
Beginning balance	82	75	75
Provision for lending-related commitments	2	6
Other	0	0
Ending balance	84	81	82
Total allowance for credit losses	1,987	1,816
Allowance for loan losses by impairment methodology
Asset-specific	(621)	(756)
Portfolio-based	2,524	2,491
Total allowance for loan losses	1,903	1,735	1,807
Loans by impairment methodology
Asset-specific	3,366	2,784
Portfolio-based	366,493	375,154
Total retained loans	369,859	377,938	376,334
Allowance for lending-related commitments by impairment methodology
Asset-specific	0	0
Portfolio-based	84	81
Total allowance for lending-related commitments	84	81	82
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	0	0
Portfolio-based	25,588	26,764
Total lending-related commitments	25,588	26,764
Credit card lending-related commitments not permitted to have an allowance for credit losses	22,400	18,600
Consumer, excluding credit card | Collateral-dependent loans
Allowance for Credit Losses
Net charge-offs/(recoveries)	0	1
Collateral-dependent loans
Loans measured at fair value of collateral less cost to sell	3,316	2,805
Credit card
Allowance for Credit Losses
Beginning balance	14,600	12,450	12,450
Gross charge-offs	6,865	6,044
Gross recoveries collected	(1,088)	(762)
Net charge-offs/(recoveries)	5,777	5,282
Provision for loan losses	6,731	6,932
Other	0	0
Ending balance	15,554	14,100	14,600
Allowance for lending-related commitments
Beginning balance	0	0	0
Provision for lending-related commitments	0	0
Other	0	0
Ending balance	0	0	0
Total allowance for credit losses	15,554	14,100
Allowance for loan losses by impairment methodology
Asset-specific	0	0
Portfolio-based	15,554	14,100
Total allowance for loan losses	15,554	14,100	14,600
Loans by impairment methodology
Asset-specific	0	0
Portfolio-based	235,475	219,542
Total retained loans	235,475	219,542
Allowance for lending-related commitments by impairment methodology
Asset-specific	0	0
Portfolio-based	0	0
Total allowance for lending-related commitments	0	0	0
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	0	0
Portfolio-based	601	0
Total lending-related commitments	601	0
Credit card lending-related commitments not permitted to have an allowance for credit losses	1,100,000	989,600
Credit card | Collateral-dependent loans
Allowance for Credit Losses
Net charge-offs/(recoveries)	0	0
Collateral-dependent loans
Loans measured at fair value of collateral less cost to sell	0	0
Wholesale
Allowance for Credit Losses
Beginning balance	7,938	8,114	8,114
Gross charge-offs	1,262	659
Gross recoveries collected	(108)	(148)
Net charge-offs/(recoveries)	1,154	511
Provision for loan losses	1,489	506
Other	5	5
Ending balance	8,278	8,114	7,938
Allowance for lending-related commitments
Beginning balance	2,019	1,899	1,899
Provision for lending-related commitments	860	162
Other	1	0
Ending balance	2,880	2,061	2,019
Total allowance for credit losses	11,158	10,175
Allowance for loan losses by impairment methodology
Asset-specific	838	499
Portfolio-based	7,440	7,615
Total allowance for loan losses	8,278	8,114	7,938
Loans by impairment methodology
Asset-specific	4,895	3,510
Portfolio-based	759,556	684,380
Total retained loans	764,451	687,890	690,396
Allowance for lending-related commitments by impairment methodology
Asset-specific	131	93
Portfolio-based	2,749	1,968
Total allowance for lending-related commitments	2,880	2,061	$ 2,019
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	1,025	619
Portfolio-based	544,764	514,313
Total lending-related commitments	545,789	514,932
Credit card lending-related commitments not permitted to have an allowance for credit losses	50,200	26,600
Wholesale | Collateral-dependent loans
Allowance for Credit Losses
Net charge-offs/(recoveries)	474	150
Collateral-dependent loans
Loans measured at fair value of collateral less cost to sell	$ 1,919	$ 1,524