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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance			$ 11,430
Balance at the end of the period	$ 11,491		11,491
Provision (benefit) for credit losses	1,085	$ (1,160)	1,762	$ (1,983)
Other
Allowance for Credit Losses [Roll Forward]
Provision (benefit) for credit losses	1	0	(5)	(2)
Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	11,308	14,017	11,430	15,564
Allowance build (release) for credit losses	200	(1,678)	81	(3,231)
Other changes	(17)	7	(20)	13
Balance at the end of the period	11,491	12,346	11,491	12,346
Financing Receivable, Allowance for Credit Loss, Writeoff	(1,383)	(1,235)	(2,704)	(2,589)
Recoveries	538	694	1,092	1,308
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery	(845)	(541)	(1,612)	(1,281)
Provision (benefit) for credit losses	1,045	(1,137)	1,693	(1,950)
Increase (Decrease) in Allowance for Credit Loss			61
Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	200	187	165	195
Balance at the end of the period	239	164	239	164
Provision (benefit) for credit losses	39	(23)	74	(31)
Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	11,730	12,510	11,730	12,510
Credit Card | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	8,280	10,072	8,345	11,191
Allowance build (release) for credit losses	(97)	(1,206)	(159)	(2,331)
Other changes	(17)	7	(20)	13
Balance at the end of the period	8,166	8,873	8,166	8,873
Financing Receivable, Allowance for Credit Loss, Writeoff	(1,009)	(967)	(1,964)	(1,960)
Recoveries	331	396	679	756
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery	(678)	(571)	(1,285)	(1,204)
Provision (benefit) for credit losses	581	(635)	1,126	(1,127)
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
Balance at the end of the period	0	0	0	0
Provision (benefit) for credit losses	0	0	0	0
Credit Card | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	8,166	8,873	8,166	8,873
Consumer Banking | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	1,902	2,498	1,918	2,715
Allowance build (release) for credit losses	145	(295)	129	(512)
Other changes	0	0	0	0
Balance at the end of the period	2,047	2,203	2,047	2,203
Financing Receivable, Allowance for Credit Loss, Writeoff	(331)	(260)	(680)	(602)
Recoveries	195	271	398	522
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery	(136)	11	(282)	(80)
Provision (benefit) for credit losses	281	(306)	411	(432)
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
Balance at the end of the period	0	0	0	0
Provision (benefit) for credit losses	0	0	0	0
Consumer Banking | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	2,047	2,203	2,047	2,203
Commercial Banking | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	1,126	1,447	1,167	1,658
Allowance build (release) for credit losses	152	(177)	111	(388)
Other changes	0	0	0	0
Balance at the end of the period	1,278	1,270	1,278	1,270
Financing Receivable, Allowance for Credit Loss, Writeoff	(43)	(8)	(60)	(27)
Recoveries	12	27	15	30
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery	(31)	19	(45)	3
Provision (benefit) for credit losses	183	(196)	156	(391)
Commercial Banking | Reserve for unfunded lending commitments
Allowance for Credit Losses [Roll Forward]
Financing Receivable, Allowance for Credit Loss, Beginning Balance	200	187	165	195
Balance at the end of the period	239	164	239	164
Provision (benefit) for credit losses	39	(23)	74	(31)
Commercial Banking | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	$ 1,517	$ 1,434	$ 1,517	$ 1,434