Derivative Financial Instruments - Master Netting (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivative Asset [Abstract]
Derivative Asset, Fair Value, Gross	$ 4,902	$ 5,841
Amount Offset	(1,714)	(2,004)
Net Amount in Consolidated Balance Sheets	3,188	3,837
Derivative, Collateral, Obligation to Return Securities	(3)	(3)
Net Amount	3,185	3,834
Derivative Liability [Abstract]
Derivative Liability, Fair Value, Gross	(3,568)	(3,663)
Amount Offset	2,994	3,108
Net amount	(574)	(555)
Held/Pledged Financial Instruments	58	35
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(516)	(520)
Derivatives Subject to Master Netting Arrangements
Derivative Asset [Abstract]
Derivative Asset, Fair Value, Gross	3,904	4,383
Amount Offset	(1,714)	(1,618)
Net Amount in Consolidated Balance Sheets	2,190	2,765
Derivative, Collateral, Obligation to Return Securities	(3)	(2)
Net Amount	2,187	2,763
Derivative Liability [Abstract]
Derivative Liability, Fair Value, Gross	(3,344)	(3,103)
Amount Offset	2,994	2,722
Net amount	(350)	(381)
Held/Pledged Financial Instruments	58	35
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(292)	(346)
Derivatives Not Subject to Master Netting Arrangement
Derivative Asset [Abstract]
Derivative Asset, Fair Value, Gross	525	705
Amount Offset	0	0
Net Amount in Consolidated Balance Sheets	525	705
Derivative, Collateral, Obligation to Return Securities	0	(1)
Net Amount	525	704
Derivative Liability [Abstract]
Derivative Liability, Fair Value, Gross	(224)	(174)
Amount Offset	0	0
Net amount	(224)	(174)
Held/Pledged Financial Instruments	0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(224)	(174)
Exchange Traded
Derivative Asset [Abstract]
Derivative Asset, Fair Value, Gross	473	753
Amount Offset	0	(386)
Net Amount in Consolidated Balance Sheets	473	367
Derivative, Collateral, Obligation to Return Securities	0	0
Net Amount	$ 473	367
Derivative Liability [Abstract]
Derivative Liability, Fair Value, Gross		(386)
Amount Offset		386
Net amount		0
Held/Pledged Financial Instruments		0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		$ 0

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, and obligation to return cash collateral under master netting arrangements.

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Fair value, after the 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 not elected to be offset.

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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 securities collateral under master netting arrangements that have not been offset against derivative liabilities.

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Fair value, after offset of derivative liability, 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, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, after offset of derivative asset, of financial liability or 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, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Fair value of asset associated with financial liability or 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, and right to receive cash collateral under master netting arrangements.

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