Derivatives Derivative Credit Risk on Freestanding Derivatives - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 2,059	$ 2,765
Derivative Liability, Fair Value, Gross Liability	2,586	2,112
Derivative, Collateral, Obligation to Return Cash	71	348
Derivative, Collateral, Right to Reclaim Cash	15	64
Customer Securities for which Entity has Right to Sell or Repledge, Fair Value of Securities Sold or Repledged	0
Accrued Liabilities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Fair Value, Gross Asset	39	55
Derivative Liability, Fair Value, Gross Liability	(23)	(8)
OTC-bilateral
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Collateral, Obligation to Return Securities	89	58
Derivative, Collateral, Right to Reclaim Securities	288	364
OTC-cleared and Exchange-traded
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Collateral, Right to Reclaim Securities	94	81
Exchange Traded
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Collateral, Right to Reclaim Securities	$ 8	$ 14

Fair value as of the balance sheet date of customer securities accepted as collateral by the entity that it has sold or re-pledged to counterparties as collateral.

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