Fair Value Disclosures (Gains (Losses) Due to Changes in Instrument-Specific Credit Risk) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value disclosure
Cumulative pre-tax DVA gain (loss) recognized in AOCI	$ 172	$ (1,831)
Borrowings \| OCI
Fair Value disclosure
Gains (losses) due to changes in instrument-specific credit risk	1,962	(903)	$ (460)
Borrowings \| Trading Revenues
Fair Value disclosure
Gains (losses) due to changes in instrument-specific credit risk	(24)	(12)	31
Loans and Other Debt \| OCI
Fair Value disclosure
Gains (losses) due to changes in instrument-specific credit risk	0	0	0
Loans and Other Debt \| Trading Revenues
Fair Value disclosure
Gains (losses) due to changes in instrument-specific credit risk	165	159	(71)
Lending Commitments \| OCI
Fair Value disclosure
Gains (losses) due to changes in instrument-specific credit risk	0	0	0
Lending Commitments \| Trading Revenues
Fair Value disclosure
Gains (losses) due to changes in instrument-specific credit risk	(3)	(2)	4
Other \| OCI
Fair Value disclosure
Gains (losses) due to changes in instrument-specific credit risk	41	(7)	0
Other \| Trading Revenues
Fair Value disclosure
Gains (losses) due to changes in instrument-specific credit risk	$ (32)	$ 0	$ 0