Allowance for Credit Losses - Summary (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Allowance for loan losses
Beginning balance	$ 22,420	$ 19,726	$ 19,726
Gross charge-offs	5,107	3,227
Gross recoveries collected	(920)	(679)
Net charge-offs/(recoveries)	4,187	2,548
Provision for loan losses	4,758	5,364
Other	0	25
Ending balance	22,991	21,980	22,420
Allowance for lending-related commitments
Beginning balance	1,974	2,382	2,382
Provision for lending-related commitments	94	(201)
Other	0	5
Ending balance	2,068	2,186	1,974
Total allowance for investment securities	177	104	128
Total allowance for credit losses	25,236	24,270
Allowance for loan losses by impairment methodology
Asset-specific	(294)	(493)
Portfolio-based	23,285	22,473
Total allowance for loan losses	22,991	21,980	22,420
Loans by impairment methodology
Asset-specific	6,317	6,026
Portfolio-based	1,266,730	1,249,662
Total retained loans	1,273,047	1,255,688	1,280,870
Allowance for lending-related commitments by impairment methodology
Asset-specific	107	65
Portfolio-based	1,961	2,121
Total allowance for lending-related commitments	2,068	2,186	1,974
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	541	332
Portfolio-based	539,232	553,836
Total lending-related commitments	539,773	554,168
CIB
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Allowance for credit losses associated with accounts receivable	278	18
Collateral-dependent loans
Allowance for loan losses
Net charge-offs/(recoveries)	137	82
Collateral-dependent loans
Loans measured at fair value of collateral less cost to sell	4,319	4,150
Cumulative effect of change in accounting principles | Accounting Standards Update 2022-02
Allowance for loan losses
Beginning balance		(587)	(587)
Allowance for loan losses by impairment methodology
Total allowance for loan losses
Consumer, excluding credit card
Allowance for loan losses
Beginning balance	1,856	2,040	2,040
Gross charge-offs	661	501
Gross recoveries collected	(343)	(247)
Net charge-offs/(recoveries)	318	254
Provision for loan losses	204	751
Other	1	0
Ending balance	1,743	2,048	1,856
Allowance for lending-related commitments
Beginning balance	75	76	76
Provision for lending-related commitments	17	52
Other	0	1
Ending balance	92	129	75
Total allowance for credit losses	1,835	2,177
Allowance for loan losses by impairment methodology
Asset-specific	(856)	(971)
Portfolio-based	2,599	3,019
Total allowance for loan losses	1,743	2,048	1,856
Loans by impairment methodology
Asset-specific	3,034	3,439
Portfolio-based	379,761	392,756
Total retained loans	382,795	396,195	397,275
Allowance for lending-related commitments by impairment methodology
Asset-specific	0	0
Portfolio-based	92	129
Total allowance for lending-related commitments	92	129	75
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	0	0
Portfolio-based	27,375	32,428
Total lending-related commitments	27,375	32,428
Credit card lending-related commitments not permitted to have an allowance for credit losses	19,800	18,400
Consumer, excluding credit card | Collateral-dependent loans
Allowance for loan losses
Net charge-offs/(recoveries)	3	5
Collateral-dependent loans
Loans measured at fair value of collateral less cost to sell	2,978	3,388
Consumer, excluding credit card | Cumulative effect of change in accounting principles | Accounting Standards Update 2022-02
Allowance for loan losses
Beginning balance		(489)	(489)
Allowance for loan losses by impairment methodology
Total allowance for loan losses
Credit card
Allowance for loan losses
Beginning balance	12,450	11,200	11,200
Gross charge-offs	3,998	2,432
Gross recoveries collected	(482)	(386)
Net charge-offs/(recoveries)	3,516	2,046
Provision for loan losses	4,266	2,546
Other	0	0
Ending balance	13,200	11,600	12,450
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	13,200	11,600
Allowance for loan losses by impairment methodology
Asset-specific	0	0
Portfolio-based	13,200	11,600
Total allowance for loan losses	13,200	11,600	12,450
Loans by impairment methodology
Asset-specific	0	0
Portfolio-based	216,100	191,348
Total retained loans	216,100	191,348
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	0	0
Total lending-related commitments	0	0
Credit card lending-related commitments not permitted to have an allowance for credit losses	964,700	881,500
Credit card | Collateral-dependent loans
Allowance for loan losses
Net charge-offs/(recoveries)	0	0
Collateral-dependent loans
Loans measured at fair value of collateral less cost to sell	0	0
Credit card | Cumulative effect of change in accounting principles | Accounting Standards Update 2022-02
Allowance for loan losses
Beginning balance		(100)	(100)
Allowance for loan losses by impairment methodology
Total allowance for loan losses
Wholesale
Allowance for loan losses
Beginning balance	8,114	6,486	6,486
Gross charge-offs	448	294
Gross recoveries collected	(95)	(46)
Net charge-offs/(recoveries)	353	248
Provision for loan losses	288	2,067
Other	(1)	25
Ending balance	8,048	8,332	8,114
Allowance for lending-related commitments
Beginning balance	1,899	2,306	2,306
Provision for lending-related commitments	77	(253)
Other	0	4
Ending balance	1,976	2,057	1,899
Total allowance for credit losses	10,024	10,389
Allowance for loan losses by impairment methodology
Asset-specific	562	478
Portfolio-based	7,486	7,854
Total allowance for loan losses	8,048	8,332	8,114
Loans by impairment methodology
Asset-specific	3,283	2,587
Portfolio-based	670,869	665,558
Total retained loans	674,152	668,145	672,472
Allowance for lending-related commitments by impairment methodology
Asset-specific	107	65
Portfolio-based	1,869	1,992
Total allowance for lending-related commitments	1,976	2,057	1,899
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	541	332
Portfolio-based	511,857	521,408
Total lending-related commitments	512,398	521,740
Credit card lending-related commitments not permitted to have an allowance for credit losses	32,600	19,300
Wholesale | Collateral-dependent loans
Allowance for loan losses
Net charge-offs/(recoveries)	134	77
Collateral-dependent loans
Loans measured at fair value of collateral less cost to sell	$ 1,341	762
Wholesale | Cumulative effect of change in accounting principles | Accounting Standards Update 2022-02
Allowance for loan losses
Beginning balance		$ 2	$ 2
Allowance for loan losses by impairment methodology
Total allowance for loan losses