Consolidated Statement of Shareholders' Equity (Unaudited) - 3 months ended Mar. 31, 2018 - USD ($) shares in Millions, $ 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, 2017			0.0	153.1	0.1
Beginning balance at Dec. 31, 2017	$ 982.9		$ 0.0	$ 1.5	$ 0.0	$ 2,911.6	$ (1,834.3)	$ (95.9)
Cumulative adjustment upon adoption of ASC 606 at Dec. 31, 2017	2.7						2.7
Balance as of December 31, 2017 (as adjusted) at Dec. 31, 2017	985.6		$ 0.0	$ 1.5	$ 0.0	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 shares withheld for taxes (in shares)					(0.1)
Incentive compensation plan shares withheld for taxes	(8.7)						(8.7)
Foreign currency translation	14.2	[1]						14.2
Unrealized gain from hedge accounting	3.2							3.2
Ending balance (in shares) at Mar. 31, 2018			0.0	151.9	0.0
Ending balance at Mar. 31, 2018	$ 996.9		$ 0.0	$ 1.5	$ 0.0	$ 2,928.5	$ (1,854.6)	$ (78.5)

[1] (1) Net of tax benefit of $0.1 million and zero for the three months ended March 31, 2018 and 2017, respectively.