Income Taxes (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 67.9
Effective Income Tax Rate Reconciliation, Transition tax, Net of Foreign Taxes Deemed Paid, Amount	11.0
Estimated Reduction, Income Tax Liability	28.0
Estimated Reduction, Net Deferred Tax Assets	19.0
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	15.0
Operating Loss Carryforwards	302.1
Deferred Tax Assets, Valuation Allowance	54.0
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	52.3
Second component of tax deductible goodwill, net of tax	1.6
Liability for Uncertain Tax Positions, Noncurrent	21.8
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	4.5
Deferred tax asset, Uncertain tax position	4.9
Unrecognized Tax Benefits, Interest on Income Taxes Expense	$ 1.5