Variable Interest Entities - Loan Delinquencies and Net Charge-offs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Securitized loans
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
90 days past due	$ 6,057	$ 9,103
Net liquidation losses	721	1,623
Securitized loans | Commercial and other
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
90 days past due	225	957
Net liquidation losses	280	114
Nonconsolidated entities
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
Securitized assets	145,500	133,303
Nonconsolidated entities | Commercial and other
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
Securitized assets	79,387	63,411
Prime/Alt-A and option ARMs | Securitized loans | Residential mortgage
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
90 days past due	3,354	4,870
Net liquidation losses	610	790
Prime/Alt-A and option ARMs | Nonconsolidated entities | Residential mortgage
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
Securitized assets	50,679	52,280
Subprime | Securitized loans | Residential mortgage
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
90 days past due	2,478	3,276
Net liquidation losses	(169)	719
Subprime | Nonconsolidated entities | Residential mortgage
Information about delinquencies, net charge-offs, and components of off-balance sheet securitized financial assets [Abstract]
Securitized assets	$ 15,434	$ 17,612