Derivative Instruments and Other Financial Instruments Used For Hedging - Derivatives Designated as Cash Flow Hedges (Details) - Designated as hedging instrument - Cash flow hedges - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Amount and location of net gains and losses
Gains (Losses) Recognized in OCI (Effective Portion)	$ (96)	$ (35)	$ (26)
Gains (Losses) Reclassified from AOCI into Income (Effective Portion)	(34)	69	167
Gains (Losses) Recognized in Income (Ineffective Portion)	(1)	3	0
Interest rate contracts
Amount and location of net gains and losses
Gains (Losses) Recognized in OCI (Effective Portion)	(96)	(35)	(26)
Interest rate contracts | Interest income
Amount and location of net gains and losses
Gains (Losses) Reclassified from AOCI into Income (Effective Portion)	(34)	69	170
Interest rate contracts | Interest expense
Amount and location of net gains and losses
Gains (Losses) Reclassified from AOCI into Income (Effective Portion)	0	0	(3)
Interest rate contracts | Noninterest expense
Amount and location of net gains and losses
Gains (Losses) Recognized in Income (Ineffective Portion)	$ (1)	$ 3	$ 0