Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Payments for income taxes, net of tax refunds received	$ (5)	$ 0	$ 0
Income tax benefit from rate change			625
AMT credit carryovers	12
Unrecognized tax benefits	$ 39	$ 141	$ 124	$ 112

Effective Income Tax Rate Reconciliation, Effect of Tax Cuts and Jobs Act of 2017, Amount

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

+ References

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

+ References

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Amount of unrecognized tax benefits.

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