v3.19.1

Income Taxes (Income Tax Contingencies) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Income Tax Disclosure [Abstract] |  |  |
Balance, beginning of period | $ (38) | $ (59) | $ (58)
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions | 7 | 0 | 0
Decreases related to prior year tax positions | 17 | 11 | 1
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions | 0 | (2) | (2)
Unrecognized Tax Benefits that Would Impact Effective Tax Rate | 0 | 12 | 0
Balance, end of period | $ (28) | $ (38) | $ (59)

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