Accumulated Other Comprehensive Loss - Reclassifications Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales	$ 917.7	$ 950.5	$ 948.3	$ 852.3	$ 854.2	$ 907.4	$ 908.8	$ 834.8	$ 3,668.8	$ 3,505.2	$ 3,390.4
Cost of goods sold	$ 629.2	$ 643.6	$ 653.6	$ 590.5	$ 595.6	$ 618.7	$ 615.3	$ 574.9	2,516.9	2,404.5	2,298.6
Total before tax									443.1	430.4	418.6
Tax (expense) benefit									(193.2)	(132.6)	(136.5)
Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) gain net of tax									(8.3)	(8.2)	(6.7)
Cash Flow Hedge (Loss) Gain
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
(Loss) gain net of tax									(0.9)	0.0	0.3
Pension and Post Retirement Benefit Plan Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from accumulated other comprehensive income, before tax									(10.9)	(13.0)
Tax benefit (expense)									3.5	4.8
(Loss) gain net of tax									(7.4)	(8.2)	$ (7.0)
Prior-service costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from accumulated other comprehensive income, before tax									0.9	0.9
Actuarial gains/(losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from accumulated other comprehensive income, before tax									(11.4)	(13.9)
Settlement and curtailment losses
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from accumulated other comprehensive income, before tax									(0.4)	0.0
Forward Contracts | Cash Flow Hedge (Loss) Gain | Reclassification out of accumulated other comprehensive income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales									(0.4)	(0.3)
Cost of goods sold									(0.9)	0.3
Total before tax									(1.3)	0.0
Tax (expense) benefit									0.4	0.0
Gain (loss) net of tax									$ (0.9)	$ 0.0