Accumulated Other Comprehensive (Loss) Income - Accumulated Other Comprehensive Loss Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Loss
Beginning balance	$ 1,566.0	$ 1,214.9	$ 1,579.3	$ 1,232.4
Ending balance	1,583.8	1,246.4	1,583.8	1,246.4
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Loss
Beginning balance	(16.8)	(45.8)	2.4	(35.9)
Other comprehensive income (loss)	7.3	7.5	(12.3)	(2.7)
Amounts reclassified from accumulated other comprehensive income (loss), net of taxes	0.3	0.4	0.7	0.7
Net current-period other comprehensive (loss) income, net of taxes	7.6	7.9	(11.6)	(2.0)
Ending balance	(9.2)	(37.9)	(9.2)	(37.9)
Foreign currency translation adjustments
Accumulated Other Comprehensive Loss
Beginning balance	(5.8)	(35.2)	13.8	(25.0)
Other comprehensive income (loss)	7.3	7.5	(12.3)	(2.7)
Amounts reclassified from accumulated other comprehensive income (loss), net of taxes	0.0	0.0	0.0	0.0
Net current-period other comprehensive (loss) income, net of taxes	7.3	7.5	(12.3)	(2.7)
Ending balance	1.5	(27.7)	1.5	(27.7)
Pension liability adjustments, net of taxes
Accumulated Other Comprehensive Loss
Beginning balance	(11.0)	(10.6)	(11.4)	(10.9)
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Amounts reclassified from accumulated other comprehensive income (loss), net of taxes	0.3	0.4	0.7	0.7
Net current-period other comprehensive (loss) income, net of taxes	0.3	0.4	0.7	0.7
Ending balance	$ (10.7)	$ (10.2)	$ (10.7)	$ (10.2)