Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Income Taxes (Textuals) [Abstract]
Effective tax rate (percent)	20.80%	56.30%
Unrecognized tax benefits from lapse of statute of limitations	$ 5
Unrecognized tax benefits, portion expected to be resolved in the next fiscal year	45
Unrecognized tax benefits that would impact effective tax rate	$ 40
State and Local Jurisdiction \| West Virginia
Income Taxes (Textuals) [Abstract]
Re-measurement in state deferred taxes		$ 126

Provision for Income Tax.

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Unrecognized Tax Benefits, Portion Expected To Be Resolved in the Next Fiscal Year

+ References

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

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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