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Income Taxes (Additional Information) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2017 USD ($)
Income Tax Disclosure [Abstract] |
Estimated income tax expense (benefit), discrete items | $ (24.4)
Estimated reduction in deferred income tax liabilities | 30.8
Estimated increase in income tax payable due to transition tax | $ 6.5

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