Allowance for Credit Losses and Reserve for Unfunded Lending Commitments - Allowance for Credit Losses and Reserve for Unfunded Lending Commitments Activity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period			$ 15,296
Provision for credit losses	$ 3,909	$ 2,490	6,592	$ 5,285
Balance at the end of the period	16,649		16,649
Translation adjustment and purchase credit deteriorated loans			0	32
Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	15,380	14,318	15,296	13,240
Charge-offs	(3,361)	(2,772)	(6,634)	(5,015)
Recoveries	717	587	1,374	1,133
Net charge-offs	(2,644)	(2,185)	(5,260)	(3,882)
Provision for credit losses	3,914	2,503	6,621	5,305
Allowance build (release) for credit losses	1,270	318	1,361	1,423
Other changes	(1)	10	(8)	46
Balance at the end of the period	16,649	14,646	16,649	14,646
Allowance for credit losses | Cumulative Effect, Period of Adoption, Adjustment
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period				(63)
Allowance for credit losses | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period				13,177
Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	134	211	158	218
Provision for credit losses	(5)	(14)	(29)	(21)
Balance at the end of the period	129	197	129	197
Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	16,778	14,843	16,778	14,843
Credit Card: | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	11,754	10,410	11,709	9,545
Charge-offs	(2,686)	(1,868)	(5,260)	(3,556)
Recoveries	428	340	795	659
Net charge-offs	(2,258)	(1,528)	(4,465)	(2,897)
Provision for credit losses	3,545	2,084	5,804	4,345
Allowance build (release) for credit losses	1,287	556	1,339	1,448
Other changes	(1)	10	(8)	46
Balance at the end of the period	13,040	10,976	13,040	10,976
Credit Card: | Allowance for credit losses | Cumulative Effect, Period of Adoption, Adjustment
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period				(63)
Credit Card: | Allowance for credit losses | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period				9,482
Credit Card: | Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	0	0	0	0
Provision for credit losses	0	0	0	0
Balance at the end of the period	0	0	0	0
Credit Card: | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	13,040	10,976	13,040	10,976
Consumer Banking: | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	2,088	2,205	2,042	2,237
Charge-offs	(636)	(526)	(1,296)	(1,057)
Recoveries	283	247	563	471
Net charge-offs	(353)	(279)	(733)	(586)
Provision for credit losses	330	259	756	534
Allowance build (release) for credit losses	(23)	(20)	23	(52)
Other changes	0	0	0	0
Balance at the end of the period	2,065	2,185	2,065	2,185
Consumer Banking: | Allowance for credit losses | Cumulative Effect, Period of Adoption, Adjustment
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period				0
Consumer Banking: | Allowance for credit losses | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period				2,237
Consumer Banking: | Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	0	0	0	0
Provision for credit losses	0	0	0	0
Balance at the end of the period	0	0	0	0
Consumer Banking: | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	2,065	2,185	2,065	2,185
Commercial Banking: | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	1,538	1,703	1,545	1,458
Charge-offs	(39)	(378)	(78)	(402)
Recoveries	6	0	16	3
Net charge-offs	(33)	(378)	(62)	(399)
Provision for credit losses	39	160	61	426
Allowance build (release) for credit losses	6	(218)	(1)	27
Other changes	0	0	0	0
Balance at the end of the period	1,544	1,485	1,544	1,485
Commercial Banking: | Allowance for credit losses | Cumulative Effect, Period of Adoption, Adjustment
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period				0
Commercial Banking: | Allowance for credit losses | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period				1,458
Commercial Banking: | Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	134	211	158	218
Provision for credit losses	(5)	(14)	(29)	(21)
Balance at the end of the period	129	197	129	197
Commercial Banking: | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	1,673	$ 1,682	$ 1,673	$ 1,682
Domestic Credit Card Portfolio Segment
Allowance for Credit Losses [Roll Forward]
Allowance build (release) for credit losses	$ 826