Accumulated Other Comprehensive Income (Loss) - Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Loss
Accumulated other comprehensive loss, beginning balance	$ (50.1)	$ (95.3)
Other comprehensive income (loss) before reclassifications and income taxes	94.3	74.0
Amounts reclassified from accumulated other comprehensive (loss) income, before income tax	(9.7)	(7.4)
Income tax (expense) benefit	2.2	(21.6)
Net current period other comprehensive income (loss), net of income taxes	86.8	45.0	$ (63.2)
Noncontrolling interest	4.6	0.2
Net current period comprehensive income (loss), net of income taxes and noncontrolling interest	91.4	45.2
Accumulated other comprehensive loss, ending balance	41.3	(50.1)	(95.3)
Foreign currency translation adjustments
Accumulated Other Comprehensive Loss
Accumulated other comprehensive loss, beginning balance	(115.3)	(95.6)
Other comprehensive income (loss) before reclassifications and income taxes	92.7	(19.9)
Amounts reclassified from accumulated other comprehensive (loss) income, before income tax	0.0	0.0
Income tax (expense) benefit	0.0	0.0
Net current period other comprehensive income (loss), net of income taxes	92.7	(19.9)
Noncontrolling interest	4.6	0.2
Net current period comprehensive income (loss), net of income taxes and noncontrolling interest	97.3	(19.7)
Accumulated other comprehensive loss, ending balance	(18.0)	(115.3)	(95.6)
Pension and postretirement liability adjustments
Accumulated Other Comprehensive Loss
Accumulated other comprehensive loss, beginning balance	66.9	0.0
Other comprehensive income (loss) before reclassifications and income taxes	2.8	92.7
Amounts reclassified from accumulated other comprehensive (loss) income, before income tax	(7.4)	(3.6)
Income tax (expense) benefit	1.1	(22.2)
Net current period other comprehensive income (loss), net of income taxes	(3.5)	66.9
Noncontrolling interest	0.0	0.0
Net current period comprehensive income (loss), net of income taxes and noncontrolling interest	(3.5)	66.9
Accumulated other comprehensive loss, ending balance	63.4	66.9	0.0
Change in fair value of derivative financial instruments
Accumulated Other Comprehensive Loss
Accumulated other comprehensive loss, beginning balance	(1.7)	0.3
Other comprehensive income (loss) before reclassifications and income taxes	(1.2)	1.2
Amounts reclassified from accumulated other comprehensive (loss) income, before income tax	(2.3)	(3.8)
Income tax (expense) benefit	1.1	0.6
Net current period other comprehensive income (loss), net of income taxes	(2.4)	(2.0)
Noncontrolling interest	0.0	0.0
Net current period comprehensive income (loss), net of income taxes and noncontrolling interest	(2.4)	(2.0)
Accumulated other comprehensive loss, ending balance	$ (4.1)	$ (1.7)	$ 0.3