Income Taxes - Changes in Gross Amounts of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions |
12 Months Ended | |||||
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Dec. 31, 2017 |
Dec. 22, 2017 |
Dec. 21, 2017 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] | ||||||
| Balance at beginning of the year | $ 103 | $ 104 | ||||
| Additions based on tax positions related to current year | 0 | 0 | ||||
| Additions for tax positions of prior years | 0 | 0 | ||||
| Reductions for tax positions of prior years | (1) | (1) | ||||
| Settlements | 0 | 0 | ||||
| U.S. tax reform rate change | (40) | 0 | ||||
| Balance at end of the year | $ 62 | $ 62 | $ 103 | $ 104 | ||
| U.S. corporate income tax rate | 21.00% | 21.00% | 35.00% | 35.00% | 35.00% | 35.00% |
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- Definition Unrecognized Tax Benefits, Decrease Resulting from Change In Enacted Tax Rate No definition available.
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- Definition Percentage of domestic federal statutory tax rate applicable to pretax income (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
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- Definition Amount of unrecognized tax benefits. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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