Income Taxes Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) $ in Millions |
12 Months Ended |
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Dec. 31, 2017
USD ($)
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| Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] | |
| Balance at January 1, 2017 | $ 55 |
| Increases related to prior year tax positions | 1 |
| Decreases related to prior year tax positions | (8) |
| Decreases related to settlements with taxing authorities | (4) |
| Increases related to current year tax positions | 6 |
| Balance at December 31, 2017 | $ 50 |
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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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