Accumulated Other Comprehensive Income (Loss) - Change in AOCI Balances (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Selling, general and administrative expense	$ 76.9	$ 70.8
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	441.9
Other comprehensive income before reclassification	3.6	4.5
Amounts reclassified from accumulated other comprehensive income	1.4	1.0
Ending balance	419.0
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(140.3)	(157.0)
Ending balance	(135.3)	(151.5)
Pension and Other Postretirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(113.9)	(108.6)
Other comprehensive income before reclassification	0.0	0.0
Amounts reclassified from accumulated other comprehensive income	1.4	0.8
Ending balance	(112.5)	(107.8)
Derivatives Designated as Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1.4	(0.1)
Other comprehensive income before reclassification	1.1	0.2
Amounts reclassified from accumulated other comprehensive income	0.0	0.2
Ending balance	2.5	0.3
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(27.8)	(48.3)
Other comprehensive income before reclassification	2.5	4.3
Amounts reclassified from accumulated other comprehensive income	0.0	0.0
Ending balance	(25.3)	(44.0)
Reclassification out of Accumulated Other Comprehensive Income | Pension and Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Selling, general and administrative expense	$ 1.6	$ 1.3