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, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance			$ 13,240
Provision for credit losses	$ 2,490	$ 1,085	5,285	$ 1,762
Balance at the end of the period	14,646		14,646
Financing Receivable Allowance For Credit Loss Translation Adjustments And Purchase Credit Deteriorated Loans			32
Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	14,318	11,308	13,240	11,430
Financing Receivable, Allowance for Credit Loss, Writeoff	(2,772)	(1,383)	(5,015)	(2,704)
Recoveries	587	538	1,133	1,092
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery	(2,185)	(845)	(3,882)	(1,612)
Provision for credit losses	2,503	1,045	5,305	1,693
Allowance build (release) for credit losses	318	200	1,423	81
Other changes	10	(17)	46	(20)
Balance at the end of the period	14,646	11,491	14,646	11,491
Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	211	200	218	165
Provision for credit losses	(14)	39	(21)	74
Balance at the end of the period	197	239	197	239
Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	14,843	11,730	14,843	11,730
Credit Card: | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	10,410	8,280	9,545	8,345
Financing Receivable, Allowance for Credit Loss, Writeoff	(1,868)	(1,009)	(3,556)	(1,964)
Recoveries	340	331	659	679
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery	(1,528)	(678)	(2,897)	(1,285)
Provision for credit losses	2,084	581	4,345	1,126
Allowance build (release) for credit losses	556	(97)	1,448	(159)
Other changes	10	(17)	46	(20)
Balance at the end of the period	10,976	8,166	10,976	8,166
Credit Card: | Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	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	10,976	8,166	10,976	8,166
Consumer Banking: | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	2,205	1,902	2,237	1,918
Financing Receivable, Allowance for Credit Loss, Writeoff	(526)	(331)	(1,057)	(680)
Recoveries	247	195	471	398
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery	(279)	(136)	(586)	(282)
Provision for credit losses	259	281	534	411
Allowance build (release) for credit losses	(20)	145	(52)	129
Other changes	0	0	0	0
Balance at the end of the period	2,185	2,047	2,185	2,047
Consumer Banking: | Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	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	2,185	2,047	2,185	2,047
Commercial Portfolio | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	1,703	1,126	1,458	1,167
Financing Receivable, Allowance for Credit Loss, Writeoff	(378)	(43)	(402)	(60)
Recoveries	0	12	3	15
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery	(378)	(31)	(399)	(45)
Provision for credit losses	160	183	426	156
Allowance build (release) for credit losses	(218)	152	27	111
Other changes	0	0	0	0
Balance at the end of the period	1,485	1,278	1,485	1,278
Commercial Portfolio | Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	211	200	218	165
Provision for credit losses	(14)	39	(21)	74
Balance at the end of the period	197	239	197	239
Commercial Portfolio | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	$ 1,682	$ 1,517	$ 1,682	$ 1,517