Consolidated Statement Of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2016		160,300,000	0
Beginning balance at Dec. 31, 2016	$ 1,047.9	$ 1.6	$ 0.0	$ 2,857.3	$ (1,671.2)	$ (139.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	523.1				523.1
Equity-based compensation expense	37.9			37.9
Stock option exercises (in shares)		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
Repurchases of common stock (in shares)		(8,900,000)
Repurchases of common stock	(534.0)	$ (0.1)			(533.9)
Dividend payments	(106.9)			0.7	(107.6)
Incentive compensation plan stock withheld for taxes (in shares)			100,000
Incentive compensation plan stock withheld for taxes	(49.6)			(7.6)	(42.0)
Foreign currency translation	43.7					43.7
Unrealized loss from hedge accounting	(0.1)					(0.1)
Realized gain from hedge accounting	0.3					0.3
Ending balance (in shares) at Dec. 31, 2017		153,100,000	100,000
Ending balance at Dec. 31, 2017	985.6	$ 1.5	$ 0.0	2,911.6	(1,831.6)	(95.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	643.0				643.0
Equity-based compensation expense	36.5			36.5
Stock option exercises (in shares)		800,000
Stock option exercises	28.6			28.6
Coworker stock purchase plan (in shares)		100,000
Coworker stock purchase plan	11.8			11.8
Repurchases of common stock (in shares)		(6,300,000)
Repurchases of common stock	(522.3)				(522.3)
Dividend payments	(139.4)			0.8	(140.2)
Incentive compensation plan stock withheld for taxes (in shares)			(100,000)
Incentive compensation plan stock withheld for taxes	(33.9)			7.6	(41.5)
Foreign currency translation	(32.7)
Unrealized loss from hedge accounting	(5.9)					(5.9)
Realized gain from hedge accounting	3.9					3.9
Ending balance (in shares) at Dec. 31, 2018		147,700,000	0
Ending balance at Dec. 31, 2018	975.2	$ 1.5	$ 0.0	2,996.9	(1,892.6)	(130.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	736.8				736.8
Equity-based compensation expense	$ 47.7			47.7
Stock option exercises (in shares)	1,065,184	1,300,000
Stock option exercises	$ 34.9			34.9
Coworker stock purchase plan (in shares)		100,000
Coworker stock purchase plan	14.9			14.9
Repurchases of common stock (in shares)		(6,100,000)
Repurchases of common stock	(657.2)	$ (0.1)			(657.1)
Dividend payments	(183.4)			0.9	(184.3)
Incentive compensation plan stock withheld for taxes	(21.4)				(21.4)
Foreign currency translation	22.4					22.4
Unrealized loss from hedge accounting	(11.3)					(11.3)
Realized gain from hedge accounting	1.7					1.7
Ending balance (in shares) at Dec. 31, 2019		143,000,000.0	0
Ending balance at Dec. 31, 2019	$ 960.3	$ 1.4	$ 0.0	$ 3,095.3	$ (2,018.6)	$ (117.8)