Income Tax 2017 Tax Act Net Benefit (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred Tax Liabilities, Net	$ 433.9
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability	$ 46.1