Derivative Instruments and Hedging Activities - Offsetting Assets (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivative assets
Derivative assets, gross amount	$ 1,221	$ 1,539
Derivative assets, offsetting financial instruments	(265)	(205)
Derivative assets, offsetting cash collateral	(247)	(874)
Total derivative assets	709	460
Derivative assets, securities not netted	0	0
Net Exposure	709	460
Derivative, collateral, obligation to return cash	440	925
Derivative, collateral, obligation to return securities	1	1
Derivative, collateral, right to reclaim cash	$ 695	$ 633

Amount of obligation to return cash collateral under master netting arrangements offset against derivative assets.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Fair value of securities received as collateral against derivative assets.

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Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

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Amount of obligation to return securities collateral under master netting arrangements that have not been offset against derivative assets.

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Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

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Fair value, after effects of master netting arrangements, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset offset against an obligation to return collateral. Includes assets not subject to a master netting arrangement and not elected to be offset.

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