Consolidated Statement of Shareholders' Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2017		153.1
Beginning balance at Dec. 31, 2017	$ 985.6	$ 1.5	$ 2,911.6	$ (1,831.6)	$ (95.9)
Shareholders' Equity (Deficit) [Roll Forward]
Net income	127.0			127.0
Equity-based compensation expense	7.1		7.1
Stock option exercises (in shares)		0.3
Stock option exercises	7.3		7.3
Coworker Stock Purchase Plan	2.4		2.4
Repurchases of common stock (in shares)		(1.5)
Repurchases of common stock	(109.2)			(109.2)
Dividends paid	(32.0)		0.1	(32.1)
Incentive compensation plan stock withheld for taxes	(8.7)			(8.7)
Foreign currency translation	14.2				14.2
Unrealized loss from hedge accounting	3.2				3.2
Ending balance (in shares) at Mar. 31, 2018		151.9
Ending balance at Mar. 31, 2018	996.9	$ 1.5	2,928.5	(1,854.6)	(78.5)
Beginning balance (in shares) at Dec. 31, 2018		147.7
Beginning balance at Dec. 31, 2018	975.2	$ 1.5	2,996.9	(1,892.6)	(130.6)
Shareholders' Equity (Deficit) [Roll Forward]
Net income	152.9			152.9
Equity-based compensation expense	12.2		12.2
Stock option exercises (in shares)		0.5
Stock option exercises	13.0		13.0
Coworker Stock Purchase Plan	3.0		3.0
Repurchases of common stock (in shares)		(1.9)
Repurchases of common stock	(177.1)			(177.1)
Dividends paid	(43.4)		0.2	(43.6)
Incentive compensation plan stock withheld for taxes	(11.6)			(11.6)
Foreign currency translation	9.9				9.9
Unrealized loss from hedge accounting	(6.8)				(6.8)
Ending balance (in shares) at Mar. 31, 2019		146.3
Ending balance at Mar. 31, 2019	$ 927.3	$ 1.5	$ 3,025.3	$ (1,972.0)	$ (127.5)