Loans - Purchased, Sold and Reclassified to Held-for-Sale (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchases	$ 346	$ 2,089	$ 1,175	$ 4,117
Sales	7,826	4,578	22,488	13,927
Retained loans reclassified to held-for-sale	919	2,185	2,832	3,763
Consumer, excluding credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchases	101	1,780	403	3,180
Sales	0	0	181	348
Retained loans reclassified to held-for-sale	522	995	771	1,822
Excluded retained loans purchased from correspondents that were originated in accordance with the Firm's underwriting standards	7,300	3,100	19,300	10,500
Credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchases	0	0	0	0
Sales	0	0	0	0
Retained loans reclassified to held-for-sale	0	787	0	787
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchases	245	309	772	937
Sales	7,826	4,578	22,307	13,579
Retained loans reclassified to held-for-sale	$ 397	$ 403	$ 2,061	$ 1,154