Allowance for Credit Losses - Summary (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance for loan losses
Beginning balance	$ 19,726	$ 16,386	$ 28,328
Gross charge-offs	7,653	4,326	4,564
Gross recoveries collected	(1,444)	(1,473)	(1,699)
Net charge-offs	6,209	2,853	2,865
Provision for loan losses	9,468	6,189	(9,071)
Other	22	4	(6)
Ending balance	22,420	19,726	16,386
Allowance for lending-related commitments
Beginning balance	2,382	2,261	2,409
Provision for lending-related commitments	(408)	120	(149)
Other	0	1	1
Ending balance	1,974	2,382	2,261
Total allowance for investment securities	128	96	42
Total allowance for credit losses	24,522	22,204	18,689
Allowance for loan losses by impairment methodology
Asset-specific	(484)	66	(89)
Portfolio-based	22,904	19,660	16,475
Total allowance for loan losses	22,420	19,726	16,386
Loans by impairment methodology
Asset-specific	5,625	14,963	17,161
Portfolio-based	1,275,245	1,074,635	993,045
Total retained loans	1,280,870	1,089,598	1,010,206
Collateral-dependent loans
Net charge-offs	6,209	2,853	2,865
Allowance for lending-related commitments by impairment methodology
Asset-specific	89	90	167
Portfolio-based	1,885	2,292	2,094
Total allowance for lending-related commitments	1,974	2,382	2,261
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	464	455	764
Portfolio-based	544,825	482,111	483,159
Total lending-related commitments	545,289	482,566	483,923
CIB
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Allowance for credit losses associated with accounts receivable	243	21
Collateral-dependent loans
Allowance for loan losses
Net charge-offs	186	(17)	71
Collateral-dependent loans
Net charge-offs	186	(17)	71
Loans measured at fair value of collateral less cost to sell	4,228	4,049	5,089
Cumulative effect of change in accounting principles | Accounting Standards Update 2022-02
Allowance for loan losses
Beginning balance	(587)
Ending balance		(587)
Allowance for loan losses by impairment methodology
Total allowance for loan losses		(587)
Consumer, excluding credit card
Allowance for loan losses
Beginning balance	2,040	1,765	3,636
Gross charge-offs	1,151	812	630
Gross recoveries collected	(519)	(543)	(619)
Net charge-offs	632	269	11
Provision for loan losses	936	543	(1,858)
Other	1	1	(2)
Ending balance	1,856	2,040	1,765
Allowance for lending-related commitments
Beginning balance	76	113	187
Provision for lending-related commitments	(1)	(37)	(75)
Other	0	0	1
Ending balance	75	76	113
Total allowance for credit losses	1,931	2,116	1,878
Allowance for loan losses by impairment methodology
Asset-specific	(876)	(624)	(665)
Portfolio-based	2,732	2,664	2,430
Total allowance for loan losses	1,856	2,040	1,765
Loans by impairment methodology
Asset-specific	3,287	11,978	13,919
Portfolio-based	393,988	288,775	281,637
Total retained loans	397,275	300,753	295,556
Collateral-dependent loans
Net charge-offs	632	269	11
Allowance for lending-related commitments by impairment methodology
Asset-specific	0	0	0
Portfolio-based	75	76	113
Total allowance for lending-related commitments	75	76	113
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	0	0	0
Portfolio-based	28,248	20,423	29,588
Total lending-related commitments	28,248	20,423	29,588
Credit card lending-related commitments not permitted to have an allowance for credit losses	17,200	13,100	15,700
Consumer, excluding credit card | Collateral-dependent loans
Allowance for loan losses
Net charge-offs	6	(33)	33
Collateral-dependent loans
Net charge-offs	6	(33)	33
Loans measured at fair value of collateral less cost to sell	3,216	3,585	4,472
Consumer, excluding credit card | Cumulative effect of change in accounting principles | Accounting Standards Update 2022-02
Allowance for loan losses
Beginning balance	(489)
Ending balance		(489)
Allowance for loan losses by impairment methodology
Total allowance for loan losses		(489)
Credit card
Allowance for loan losses
Beginning balance	11,200	10,250	17,800
Gross charge-offs	5,491	3,192	3,651
Gross recoveries collected	(793)	(789)	(939)
Net charge-offs	4,698	2,403	2,712
Provision for loan losses	6,048	3,353	(4,838)
Other	0	0	0
Ending balance	12,450	11,200	10,250
Allowance for lending-related commitments
Beginning balance	0	0	0
Provision for lending-related commitments	0	0	0
Other	0	0	0
Ending balance	0	0	0
Total allowance for credit losses	12,450	11,200	10,250
Allowance for loan losses by impairment methodology
Asset-specific	0	223	313
Portfolio-based	12,450	10,977	9,937
Total allowance for loan losses	12,450	11,200	10,250
Loans by impairment methodology
Asset-specific	0	796	987
Portfolio-based	211,123	184,379	153,309
Total retained loans	211,123	185,175	154,296
Collateral-dependent loans
Net charge-offs	4,698	2,403	2,712
Allowance for lending-related commitments by impairment methodology
Asset-specific	0	0	0
Portfolio-based	0	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	0
Portfolio-based	0	0	0
Total lending-related commitments	0	0	0
Credit card lending-related commitments not permitted to have an allowance for credit losses	915,700	821,300	730,500
Credit card | Collateral-dependent loans
Allowance for loan losses
Net charge-offs	0	0	0
Collateral-dependent loans
Net charge-offs	0	0	0
Loans measured at fair value of collateral less cost to sell	0	0	0
Credit card | Cumulative effect of change in accounting principles | Accounting Standards Update 2022-02
Allowance for loan losses
Beginning balance	(100)
Ending balance		(100)
Allowance for loan losses by impairment methodology
Total allowance for loan losses		(100)
Wholesale
Allowance for loan losses
Beginning balance	6,486	4,371	6,892
Gross charge-offs	1,011	322	283
Gross recoveries collected	(132)	(141)	(141)
Net charge-offs	879	181	142
Provision for loan losses	2,484	2,293	(2,375)
Other	21	3	(4)
Ending balance	8,114	6,486	4,371
Allowance for lending-related commitments
Beginning balance	2,306	2,148	2,222
Provision for lending-related commitments	(407)	157	(74)
Other	0	1	0
Ending balance	1,899	2,306	2,148
Total allowance for credit losses	10,013	8,792	6,519
Allowance for loan losses by impairment methodology
Asset-specific	392	467	263
Portfolio-based	7,722	6,019	4,108
Total allowance for loan losses	8,114	6,486	4,371
Loans by impairment methodology
Asset-specific	2,338	2,189	2,255
Portfolio-based	670,134	601,481	558,099
Total retained loans	672,472	603,670	560,354
Collateral-dependent loans
Net charge-offs	879	181	142
Allowance for lending-related commitments by impairment methodology
Asset-specific	89	90	167
Portfolio-based	1,810	2,216	1,981
Total allowance for lending-related commitments	1,899	2,306	2,148
Off-Balance Sheet Lending-Related Financial Instruments, Guarantees and Other Commitments [Abstract]
Asset-specific	464	455	764
Portfolio-based	516,577	461,688	453,571
Total lending-related commitments	517,041	462,143	454,335
Credit card lending-related commitments not permitted to have an allowance for credit losses	19,700	9,800	32,100
Wholesale | Collateral-dependent loans
Allowance for loan losses
Net charge-offs	180	16	38
Collateral-dependent loans
Net charge-offs	180	16	38
Loans measured at fair value of collateral less cost to sell	1,012	464	$ 617
Wholesale | Cumulative effect of change in accounting principles | Accounting Standards Update 2022-02
Allowance for loan losses
Beginning balance	$ 2
Ending balance		2
Allowance for loan losses by impairment methodology
Total allowance for loan losses		$ 2