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Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
NOLs without an expiration date	$ 1,300
Unrecognized tax benefits	53	$ 39	$ 21
Unrecognized tax benefits that would impact effective tax rate if recognized	53
2030
Income Taxes [Line Items]
NOL carry forwards	700
2033
Income Taxes [Line Items]
NOL carry forwards	500
Thereafter
Income Taxes [Line Items]
NOL carry forwards	500
Federal
Income Taxes [Line Items]
NOL carry forwards	3,000
State
Income Taxes [Line Items]
NOL carry forwards	100
NOL carry forwards, valuation allowance	$ 45
State | Minimum
Income Taxes [Line Items]
NOL expiration period	5 years
State | Maximum
Income Taxes [Line Items]
NOL expiration period	20 years

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Income Taxes [Line Items]

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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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 unrecognized tax benefits.

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