Stockholders' Equity - Before Tax and After Tax Amounts of Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Before Tax
Other comprehensive income (loss)	$ (171.5)	$ 60.0
Tax (Expense) Benefit
Other comprehensive income (loss)	(0.3)	(0.4)
After Tax
Total other comprehensive (loss) income	(171.8)	59.6
Foreign Currency Adjustment
Before Tax
Other comprehensive income (loss)	(172.6)	58.5
Tax (Expense) Benefit
Other comprehensive income (loss)	0.0	0.0
After Tax
Total other comprehensive (loss) income	(172.6)	58.5
Pension and Postretirement Adjustment
Before Tax
Other comprehensive income (loss)	1.1	1.5
Other comprehensive income (loss) before reclassifications	2.1	2.8
Reclassification from accumulated other comprehensive income	(1.0)	(1.3)
Tax (Expense) Benefit
Other comprehensive income (loss)	(0.3)	(0.4)
Other comprehensive income (loss) before reclassifications	(0.6)	(0.7)
Reclassification from accumulated other comprehensive income	0.3	0.3
After Tax
Total other comprehensive (loss) income	0.8	1.1
Other comprehensive income (loss) before reclassifications	1.5	2.1
Reclassification from accumulated other comprehensive income	$ (0.7)	$ (1.0)