Accumulated Other Comprehensive Income (Rollforward) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017	$ (461.1)
Other comprehensive income (loss) before reclassifications, net of tax	(10.0)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	4.5
Balance at June 30, 2018	(466.6)
Derivative Financial Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017	0.2
Other comprehensive income (loss) before reclassifications, net of tax	1.4
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	2.1
Balance at June 30, 2018	3.7
Foreign Currency Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017	(305.4)
Other comprehensive income (loss) before reclassifications, net of tax	(14.1)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0.0
Balance at June 30, 2018	(319.5)
Unrecognized Pension and Other Post-retirement Benefit Costs
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at December 31, 2017	(155.9)
Other comprehensive income (loss) before reclassifications, net of tax	2.7
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	2.4
Balance at June 30, 2018	$ (150.8)