Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Details) $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	$ 1,647.9
Other comprehensive income (loss) before reclassifications	(16.1)
Amounts reclassified from accumulated other comprehensive loss	5.8
Current period other comprehensive income (loss)	(10.3)
Ending equity	1,771.8
Cash flow hedge (loss) gain
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(0.8)
Other comprehensive income (loss) before reclassifications	0.7
Amounts reclassified from accumulated other comprehensive loss	0.0
Current period other comprehensive income (loss)	0.7
Ending equity	(0.1)
Unrealized gain (loss) on available-for- sale securities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(0.6)
Other comprehensive income (loss) before reclassifications	(0.4)
Amounts reclassified from accumulated other comprehensive loss	0.0
Current period other comprehensive income (loss)	(0.4)
Ending equity	(1.0)
Pension and post retirement benefit plan adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(176.5)
Other comprehensive income (loss) before reclassifications	5.1
Amounts reclassified from accumulated other comprehensive loss	5.8
Current period other comprehensive income (loss)	10.9
Ending equity	(165.6)
Cumulative translation adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(91.9)
Other comprehensive income (loss) before reclassifications	(21.5)
Amounts reclassified from accumulated other comprehensive loss	0.0
Current period other comprehensive income (loss)	(21.5)
Ending equity	(113.4)
AOCI Attributable to Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(269.8)
Ending equity	$ (280.1)

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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