Shareholder's Equity - Change in Shareholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 1,854.5	$ 1,573.2
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201613Member
Net income	151.2	74.3
Activity related to stock-based compensation	$ 2.5	12.8
Share purchased under share repurchase program (in shares)	479,000
Shares purchased under share repurchase program	$ (137.1)	(115.5)
Dividends declared	(12.5)	(11.8)
Other comprehensive loss, net of tax	(29.6)	(42.7)
Balance, end of period	$ 1,829.0	1,490.2	$ 1,573.2
Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period		$ (0.1)
Balance, end of period			$ (0.1)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance (in shares)	75,300,000	75,300,000
Balance, beginning of period	$ 18.8	$ 18.8
Balance (in shares)	75,300,000	75,300,000	75,300,000
Balance, end of period	$ 18.8	$ 18.8	$ 18.8
Capital in Excess of Par Value
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	267.3	272.7
Activity related to stock-based compensation	(20.6)	(5.1)
Balance, end of period	$ 246.7	$ 267.6	$ 272.7
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance (in shares)	1,300,000	1,200,000
Balance, beginning of period	$ (167.7)	$ (118.1)
Activity related to stock -based compensation (in shares)	(300,000)	(300,000)
Activity related to stock-based compensation	$ 23.1	$ 17.9
Share purchased under share repurchase program (in shares)	500,000	800,000
Shares purchased under share repurchase program	$ (137.1)	$ (115.5)
Balance (in shares)	1,500,000	1,700,000	1,200,000
Balance, end of period	$ (281.7)	$ (215.7)	$ (118.1)
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	1,846.7	1,549.4
Net income	151.2	74.3
Dividends declared	(12.5)	(11.8)
Balance, end of period	1,985.4	1,611.8	1,549.4
Retained earnings | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period		(0.1)
Balance, end of period			(0.1)
Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(110.6)	(149.6)
Other comprehensive loss, net of tax	(29.6)	(42.7)
Balance, end of period	$ (140.2)	$ (192.3)	$ (149.6)