Income Taxes - Valuation Allowances (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of year				$ 98.9				$ 62.8	$ 98.9	$ 62.8	$ 45.7
Expiring tax credits									(0.6)	(0.4)	(0.4)
Acquisitions and dispositions									(0.7)	(3.4)	(0.3)
Changes in judgment about deferred tax assets(a)									0.0	(1.8)	2.6
Income from continuing operations	$ 34.9	$ 17.5	$ (107.8)	$ 22.1	$ (52.0)	$ 19.9	$ 14.3	$ 34.7	(33.3)	16.9	36.2
Other comprehensive loss									(16.5)	(18.8)	(15.8)
Foreign currency exchange effects									(2.7)	(2.4)	(8.5)
End of year	100.7				98.9				100.7	98.9	62.8
Retained earnings	$ 429.1				$ 564.9				429.1	564.9
Valuation Allowance of Deferred Tax Assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Income from continuing operations									6.1	43.9	20.5
Other comprehensive loss									(0.3)	0.2	0.7
Retained earnings									$ 0.0	$ 0.0	2.5
Retained earnings											$ 2.5