Accumulated Other Comprehensive (Loss) Income (Components of accumulated comprehensive loss) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 353,200,000	$ 316,200,000	$ 357,900,000	$ 349,600,000
Currency translation	(5,500,000)	12,600,000	(8,200,000)	(1,100,000)
Pension and OPEB activity, net of tax	200,000	300,000	600,000	1,200,000
Ending balance	337,700,000	334,000,000.0	337,700,000	334,000,000.0
Income taxes provided on currency translation as foreign earnings permanently reinvested	0	0	0	0
Cumulative Translation Adjustment
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(11,000,000.0)	(36,100,000)	(8,300,000)	(22,400,000)
Ending balance	(16,500,000)	(23,500,000)	(16,500,000)	(23,500,000)
Pension and Postretirement Benefits
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(9,400,000)	(13,700,000)	(9,800,000)	(14,600,000)
Ending balance	(9,200,000)	(13,400,000)	(9,200,000)	(13,400,000)
Accumulated Other Comprehensive (Loss) Income
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(20,400,000)	(49,800,000)	(18,100,000)	(37,000,000.0)
Ending balance	$ (25,700,000)	$ (36,900,000)	$ (25,700,000)	$ (36,900,000)