CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Treasury Stock
Balance at Dec. 31, 2018	$ 1,211.6	$ 0.9	$ 1,545.9	$ (224.2)	$ (111.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	28.6
Earnings (loss) from continuing operations	28.6
Other comprehensive earnings, net of tax	(3.6)
Other comprehensive loss, net of tax	(3.6)				(3.6)
Stock-based compensation expense	19.2		19.2
Common stock issued for exercise of stock options and other	7.5		7.5
Tax on restricted stock unit vesting	(6.0)		(6.0)
Balance at Sep. 30, 2019	1,257.3	0.9	1,566.6	(195.6)	(114.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(0.1)
Balance at Jun. 30, 2019	1,227.2	0.9	1,556.2	(221.0)	(108.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	25.4			25.4
Earnings (loss) from continuing operations	25.4
Other comprehensive earnings, net of tax	(5.7)
Other comprehensive loss, net of tax					(5.7)
Stock-based compensation expense	5.2		5.2
Common stock issued for exercise of stock options and other	5.7		5.7
Tax on restricted stock unit vesting	(0.5)		(0.5)
Balance at Sep. 30, 2019	1,257.3	0.9	1,566.6	(195.6)	(114.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(0.2)
Treasury Stock, Value	0.0
Balance at Dec. 31, 2019	1,288.5	0.9	1,574.7	(175.1)	(112.0)	$ 0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	(23.0)
Earnings (loss) from continuing operations	(26.7)			(26.7)
Other comprehensive earnings, net of tax	6.0
Other comprehensive loss, net of tax	6.0				6.0
Repurchase of common stock	(15.0)					(15.0)
Stock-based compensation expense	12.4		12.4
Common stock issued for exercise of stock options and other	1.8		1.8
Tax on restricted stock unit vesting	(6.1)		(6.1)
Balance at Sep. 30, 2020	1,264.6	0.9	1,582.8	(198.1)	(106.0)	(15.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	0.1
Balance at Jun. 30, 2020	1,243.8	0.9	1,578.0	(203.7)	(116.4)	(15.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	5.6			5.6
Earnings (loss) from continuing operations	5.6			5.6
Other comprehensive earnings, net of tax	10.4				10.4
Other comprehensive loss, net of tax					10.4
Stock-based compensation expense	4.8		4.8
Common stock issued for exercise of stock options and other	0.1		0.1
Tax on restricted stock unit vesting	(0.1)		(0.1)
Balance at Sep. 30, 2020	1,264.6	$ 0.9	$ 1,582.8	$ (198.1)	$ (106.0)	$ (15.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	0.1
Treasury Stock, Value	$ 15.0