Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 156	$ (271)	$ 286	$ (118)
Effective tax rate	34.00%	(38.00%)	29.00%	(9.00%)
Unrecognized tax benefits	$ 383		$ 383		$ 375
Unrecognized tax benefits, decreases resulting from current period tax positions			106
Unrecognized tax benefits, income tax penalties and interest accrued	69		69		$ 58
Legal entity restructuring, one-time non-cash deferred tax benefit	$ 0	$ 455	$ 0	$ 455

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

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Amount 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 nondeductible restructuring charges.

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Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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