Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Effective tax rate	(36.00%)	(254.00%)
Discrete tax benefit	$ 408	$ 426
Valuation allowance related to operating loss	$ 87
Valuation allowance decreased during the period		$ 522

Effective Income Tax Reconciliation, Discrete Tax Expense (Benefit), Amount

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.4-08.(h)(2))
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- Definition

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.

+ References

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- Definition

Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
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