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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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