Loans - By Portfolio Segment (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loan balances by portfolio segment:
Retained loans		$ 960,506	$ 945,601	$ 969,415
Held-for-sale		7,873	7,064
At fair value		44,474	44,955
Total	[1]	1,012,853	997,620
Accrued interest receivables		2,900	2,900
Accrued interest receivables written off		121	50
Consumer, excluding credit card
Loan balances by portfolio segment:
Retained loans		302,127	294,999	335,776
Held-for-sale		1,305	3,002
At fair value		15,147	19,816
Total		318,579	317,817
Credit card
Loan balances by portfolio segment:
Retained loans		143,432	168,924
Held-for-sale		784	0
At fair value		0	0
Total		144,216	168,924
Wholesale
Loan balances by portfolio segment:
Retained loans		514,947	481,678	$ 477,023
Held-for-sale		5,784	4,062
At fair value		29,327	25,139
Total		$ 550,058	$ 510,879

[1] In the third quarter of 2020, the Firm reclassified certain fair value option elected lending-related positions from trading assets to loans and other assets. Prior-period amounts have been revised to conform with the current presentation.