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, 2015		$ 2,347.4	$ 78.7	$ 293.4	$ 8.0	$ (87.1)	$ 2,381.8	$ (327.4)
Balance (in shares) at Dec. 31, 2015			64,051,600					14,383,241
Increase (Decrease) in Shareholders' Equity
Net income		68.5					68.5
Other comprehensive loss, net of tax		10.4				10.4
Cash dividends - $0.30 and $0.35 for the three months ended March 31, 2016 and 2017, respectively		(19.5)					(19.5)
Repurchases of common stock		(28.5)						$ (28.5)
Repurchases of common stock (in shares)			(331,747)					331,747
Issuances for stock based compensation (1)	[1]	9.2		4.8	2.4			$ 2.0
Issuances for stock based compensation (in shares)	[1]		241,259					(242,182)
Balance at the end of the period at Mar. 31, 2016		2,387.5	$ 78.7	298.2	10.4	(76.7)	2,430.8	$ (353.9)
Balance (in shares) at Mar. 31, 2016			63,961,112					14,472,806
Balance at the beginning of the period at Dec. 31, 2016		$ 2,466.9	$ 78.7	335.3	10.3	(122.2)	2,547.4	$ (382.6)
Balance (in shares) at Dec. 31, 2016		64,257,182	64,257,182					14,178,801
Increase (Decrease) in Shareholders' Equity
Net income		$ 61.8					61.8
Other comprehensive loss, net of tax		11.7				11.7
Cash dividends - $0.30 and $0.35 for the three months ended March 31, 2016 and 2017, respectively		(22.7)					(22.7)
Issuances for stock based compensation (1)	[1]	0.5		3.2	1.6			$ (4.3)
Issuances for stock based compensation (in shares)	[1]		111,568					(111,230)
Balance at the end of the period at Mar. 31, 2017		$ 2,518.2	$ 78.7	$ 338.5	$ 11.9	$ (110.5)	$ 2,586.5	$ (386.9)
Balance (in shares) at Mar. 31, 2017		64,368,750	64,368,750					14,067,571

[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.