Loans - Purchased, Sold and Reclassified to Held-for-Sale (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchases	$ 593	$ 1,064	$ 1,373	$ 3,233
Sales	12,256	7,334	26,359	11,504
Retained loans reclassified to held-for-sale	1,872	392	6,486	1,296
Consumer, excluding credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchases	234	532	785	1,603
Sales	6,856	2,391	15,514	2,872
Retained loans reclassified to held-for-sale	948	0	5,061	36
Excluded retained loans purchased from correspondents that were originated in accordance with the Firm's underwriting standards	4,300	5,300	7,500	8,900
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	0	0	0
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchases	359	532	588	1,630
Sales	5,400	4,943	10,845	8,632
Retained loans reclassified to held-for-sale	$ 924	$ 392	$ 1,425	$ 1,260