Income Taxes (Summary Of Detail Of Tax Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	$ 50	$ 73
Deferred Tax Assets, Net		$ 20
General Business Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax Credit Carryforward, Deferred Tax Asset	12
Tax Credit Carryforward, Valuation Allowance	0
Deferred Tax Assets, Net	12
Net Operating Losses States Date Range One [Member]
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	23
Operating Loss Carryforwards, Valuation Allowance	(11)
Deferred Tax Assets, Net	12
Pre Tax Earnings Necessary To Realize	253
Net Operating Losses States Date Range Two [Member]
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	20
Operating Loss Carryforwards, Valuation Allowance	(16)
Deferred Tax Assets, Net	4
Pre Tax Earnings Necessary To Realize	65
Net Operating Losses States Date Range Three [Member]
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	5
Operating Loss Carryforwards, Valuation Allowance	(5)
Deferred Tax Assets, Net	0
Pre Tax Earnings Necessary To Realize	0
Other Credits States Date Range One [Member]
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	2
Operating Loss Carryforwards, Valuation Allowance	0
Deferred Tax Assets, Net	$ 2

Pre-Tax Earnings Necessary to Realize

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards.

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The portion of the valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from net operating loss carryforwards for which it is more likely than not that a tax benefit will not be realized.

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Amount of valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from tax credit carryforwards for which it is more likely than not that a tax benefit will not be realized.

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