Variable Interest Entities - Credit Card Securitizations (Details) - Firm-sponsored credit card trusts - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Minimum undivided interest in credit card trusts	16.00%	22.00%
Undivided interests in Firm-sponsored credit card securitization trusts	$ 8,900,000,000	$ 13,600,000,000
Senior securities
Variable Interest Entity [Line Items]
Undivided interests in Firm-sponsored credit card securitization trusts	0	0
Subordinated securities
Variable Interest Entity [Line Items]
Undivided interests in Firm-sponsored credit card securitization trusts	$ 5,300,000,000	$ 5,300,000,000
Minimum
Variable Interest Entity [Line Items]
Minimum undivided interest in credit card trusts	5.00%