Accumulated Other Comprehensive (Loss) Income (Components of accumulated comprehensive loss) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 349.6	$ 312.6
Currency translation	(16.6)	0.7
Pension and OPEB activity, net of tax	0.5	5.3
Ending balance	331.6	329.3
Cumulative Translation Adjustment
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(22.4)	(21.3)
Currency translation	(16.6)	0.7
Ending balance	(39.0)	(20.6)
Pension and Postretirement Benefits
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(14.6)	(19.6)
Pension and OPEB activity, net of tax	0.5	5.3
Ending balance	(14.1)	(14.3)
Total
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(37.0)	(40.9)
Ending balance	$ (53.1)	$ (34.9)

Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]

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- Definition

Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan.

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- Definition

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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