Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Effective income tax rate	22.20%	12.80%	19.30%	18.50%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%
Tax Adjustments, Settlements, and Unusual Provisions		$ (202)	$ (119)	$ (153)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities			$ 119

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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