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
	Mar. 31, 2024	Mar. 31, 2023
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	$ 15,296
Provision for credit losses	2,683	$ 2,795
Balance at the end of the period	15,380
Allowance for credit loss for purchased credit-deteriorated		32
Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	15,296	13,240
Charge-offs	(3,273)	(2,243)
Recoveries	657	546
Net charge-offs	(2,616)	(1,697)
Provision for credit losses	2,707	2,802
Allowance build (release) for credit losses	91	1,105
Other changes	(7)	36
Balance at the end of the period	15,380	14,318
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	158	218
Provision for credit losses	(24)	(7)
Balance at the end of the period	134	211
Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	15,514	14,529
Credit Card: | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	11,709	9,545
Charge-offs	(2,574)	(1,688)
Recoveries	367	319
Net charge-offs	(2,207)	(1,369)
Provision for credit losses	2,259	2,261
Allowance build (release) for credit losses	52	892
Other changes	(7)	36
Balance at the end of the period	11,754	10,410
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
Provision for credit losses	0	0
Balance at the end of the period	0	0
Credit Card: | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	11,754	10,410
Consumer Banking: | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	2,042	2,237
Charge-offs	(660)	(531)
Recoveries	280	224
Net charge-offs	(380)	(307)
Provision for credit losses	426	275
Allowance build (release) for credit losses	46	(32)
Other changes	0	0
Balance at the end of the period	2,088	2,205
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
Provision for credit losses	0	0
Balance at the end of the period	0	0
Consumer Banking: | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	2,088	2,205
Commercial Banking: | Allowance for credit losses
Allowance for Credit Losses [Roll Forward]
Balance at beginning of the period	1,545	1,458
Charge-offs	(39)	(24)
Recoveries	10	3
Net charge-offs	(29)	(21)
Provision for credit losses	22	266
Allowance build (release) for credit losses	(7)	245
Other changes	0	0
Balance at the end of the period	1,538	1,703
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	158	218
Provision for credit losses	(24)	(7)
Balance at the end of the period	134	211
Commercial Banking: | Combined allowance and reserve
Allowance for Credit Losses [Roll Forward]
Balance at the end of the period	$ 1,672	$ 1,914