Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Derivative [Line Items]
Reclassification from AOCI, before Tax	$ 23	$ 6
Reclassification from AOCI, Net of Tax	3	$ 5
Total loss to be reclassified during next 12 months	8
Margin cash collateral received from counterparties that was not offset against derivative assets	37		$ 10
Margin cash collateral provided to counterparties that was not offset against derivative assets or liabilities	$ 330		$ 360

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount before tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.

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Amount after tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.

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