Condensed Consolidated Statement of Shareholders' Equity (Unaudited) - USD ($) $ in Millions		Total	Common Stock	Additional Paid-In Capital	Deferred Compensation Equity	Accumulated Other Comprehensive Income (loss)	Retained Earnings	Shares in Treasury
Balance at the beginning of the period at Dec. 31, 2018		$ 2,597.4	$ 78.7	$ 383.8	$ 8.0	$ (122.1)	$ 3,351.4	$ (1,102.4)
Balance (in shares) at Dec. 31, 2018			57,900,000					20,500,000
Increase (Decrease) in Shareholders' Equity
Net income		79.4					79.4
Other comprehensive income (loss), net of tax		6.2				6.2
Cash dividends		(23.3)					(23.3)
Repurchases of common stock		(149.9)						$ (149.9)
Repurchases of common stock (in shares)			(1,300,000)					1,300,000
Issuances and deferrals. net for stock based compensation (1)	[1]	14.9		6.3	(0.2)			$ 8.8
Issuances and deferrals, net for stock based compensation (in shares)	[1]		200,000					(200,000)
Balance at the end of the period at Mar. 31, 2019		2,524.7	$ 78.7	390.1	7.8	(115.9)	3,407.5	$ (1,243.5)
Balance (in shares) at Mar. 31, 2019			56,800,000					21,600,000
Balance at the beginning of the period at Dec. 31, 2019		$ 2,642.8	$ 78.7	413.7	$ 2.9	(124.1)	3,721.3	$ (1,449.7)
Balance (in shares) at Dec. 31, 2019		55,700,000	55,700,000					22,700,000
Increase (Decrease) in Shareholders' Equity
Net income		$ 61.8					61.8
Other comprehensive income (loss), net of tax		(45.5)				(45.5)
Cash dividends		(28.3)					(28.3)
Repurchases of common stock		(125.3)						$ (125.3)
Repurchases of common stock (in shares)			(1,000,000.0)					1,000,000.0
Issuances and deferrals. net for stock based compensation (1)	[1]	13.0		5.0				$ 7.5
Issuances and deferrals, net for stock based compensation (in shares)	[1]		200,000		500,000			(200,000)
Balance at the end of the period at Mar. 31, 2020		$ 2,518.5	$ 78.7	$ 418.7	$ 3.4	$ (169.6)	$ 3,754.8	$ (1,567.5)
Balance (in shares) at Mar. 31, 2020		54,900,000	54,900,000					23,500,000

[1] Issuances and deferrals, net for stock based compensation reflects share activity related to option exercises, restricted and performance shares vested and net issuances and deferrals associated with deferred compensation equity.