Income Taxes (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Valuation allowance	$ 55
Net of federal benefit	44
Deferred Tax Assets, Net, Current	2	$ 0
Accounting Standards Update 2014-09 [Member]
Income Tax Contingency [Line Items]
Income tax benefit	$ 3

Deferred Tax Assets, Valuation Allowance, Net Of Federal Benefit

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- Definition

Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, netted by jurisdiction and classified as current.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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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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