Consolidated Statement Of Shareholders' Equity - USD ($) $ in Millions	Total		Preferred Stock	Common Stock	Treasury Stock	Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2014			0	172,200,000	0
Beginning balance at Dec. 31, 2014	$ 936.5		$ 0.0	$ 1.7	$ 0.0	$ 2,711.9	$ (1,760.5)	$ (16.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation expense	28.3					28.3
Stock option exercises (in shares)				100,000
Stock option exercises	2.4					2.4
Common stock issued for equity-based compensation (in shares)				300,000
Common stock issued for equity-based compensation	0.0					0.0
Excess tax benefits from equity-based compensation	0.6					0.6
Coworker Stock Purchase Plan (in shares)				300,000
Coworker Stock Purchase Plan	8.7					8.7
Common stock issued for acquisition of business (in shares)				1,600,000
Common stock issued for acquisition of business	55.0					55.0
Dividends paid	(52.9)						(52.9)
Net income	403.1						403.1
Repurchases of common stock (in shares)				(6,300,000)
Repurchases of common stock	(241.3)						(241.3)
Foreign currency translation	(44.5)	[1]						(44.5)
Ending balance (in shares) at Dec. 31, 2015			0	168,200,000	0
Ending balance at Dec. 31, 2015	1,095.9		$ 0.0	$ 1.7	$ 0.0	2,806.9	(1,651.6)	(61.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation expense	33.2					33.2
Stock option exercises (in shares)				400,000
Stock option exercises	7.4					7.4
Common stock issued for equity-based compensation (in shares)				200,000
Common stock issued for equity-based compensation	0.0
Coworker Stock Purchase Plan (in shares)				200,000
Coworker Stock Purchase Plan	9.3					9.3
Dividends paid	(78.7)					0.5	(79.2)
Net income	424.4						424.4
Repurchases of common stock (in shares)				(8,700,000)
Repurchases of common stock	(367.5)			$ (0.1)			(367.4)
Foreign currency translation	(78.5)	[1]						(78.5)
Ending balance (in shares) at Dec. 31, 2016			0	160,300,000	0
Ending balance at Dec. 31, 2016	1,045.5		$ 0.0	$ 1.6	$ 0.0	2,857.3	(1,673.8)	(139.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation expense	$ 37.9					37.9
Stock option exercises (in shares)	476,520			1,500,000
Stock option exercises	$ 13.0					13.0
Coworker Stock Purchase Plan (in shares)				200,000
Coworker Stock Purchase Plan	10.3					10.3
Dividends paid	(106.9)					0.7	(107.6)
Incentive compensation plan shares withheld for taxes (in shares)					100,000
Incentive compensation plan shares withheld for taxes	(49.6)					(7.6)	(42.0)
Net income	523.0						523.0
Repurchases of common stock (in shares)				(8,900,000)
Repurchases of common stock	(534.0)			$ (0.1)			(533.9)
Unrealized gain from hedge accounting	0.2							0.2
Foreign currency translation	43.5	[1]						43.5
Ending balance (in shares) at Dec. 31, 2017			0	153,100,000	100,000
Ending balance at Dec. 31, 2017	$ 982.9		$ 0.0	$ 1.5	$ 0.0	$ 2,911.6	$ (1,834.3)	$ (95.9)

[1] Net of tax expense of $0.2 million, $0.2 million and $0.3 million, respectively.