Commitments and Contingencies - Representations and Warranties Obligations and Corporate Guarantees (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Claims related to loans in specific private-label securitization groups	$ 10,700	$ 14,400
New purchase claims	461
Claims resolved	4,200
Time-barred repurchase claims resolved	2,100
Representations and Warranties Obligations and Corporate Guarantees
Loss Contingencies [Line Items]
Reserve for representations and warranties and corporate guarantees	1,800	2,000
Private-Label Securitization Trustees
Loss Contingencies [Line Items]
Claims related to loans in specific private-label securitization groups	3,700	$ 6,200
Monolines
Loss Contingencies [Line Items]
Claims related to loans in specific private-label securitization groups	$ 1,600