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, 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)	(28.6)			(28.6)
Earnings (loss) from continuing operations	(32.3)
Other comprehensive (loss) earnings, net of tax	(4.4)
Other comprehensive loss, net of tax					(4.4)
Treasury Stock, Value, Acquired, Cost Method	(15.0)					(15.0)
Stock-based compensation expense	7.6		7.6
Common stock issued for exercise of stock options and other	1.7		1.7
Tax on restricted stock unit vesting	(6.0)		(6.0)
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]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	0.0
Balance at Mar. 31, 2020	1,253.8	0.9	1,572.8	(184.2)	(120.7)	(15.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	(19.5)			(19.5)
Earnings (loss) from continuing operations	(19.5)
Other comprehensive (loss) earnings, net of tax	4.3
Other comprehensive loss, net of tax					4.3
Stock-based compensation expense	4.1		4.1
Common stock issued for exercise of stock options and other	1.3		1.3
Tax on restricted stock unit vesting	(0.2)		(0.2)
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]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(0.2)
Treasury Stock, Value	16.2
Balance at Dec. 31, 2020	1,303.5		1,587.8	(168.5)	(100.5)	(16.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	30.1
Earnings (loss) from continuing operations	29.9			29.9
Other comprehensive (loss) earnings, net of tax	(3.9)
Other comprehensive loss, net of tax					(3.9)
Treasury Stock, Value, Acquired, Cost Method	(20.0)					(20.0)
Stock-based compensation expense	18.5		18.5
Common stock issued for exercise of stock options and other	10.5		10.5
Tax on restricted stock unit vesting	(6.6)		(6.6)
Balance at Jun. 30, 2021	1,332.1	0.9	1,610.2	(138.4)	(104.4)	(36.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(0.2)
Balance at Mar. 31, 2021	1,323.7	0.9	1,600.7	(156.0)	(105.7)	(16.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	17.6			17.6
Earnings (loss) from continuing operations	17.4			17.4
Other comprehensive (loss) earnings, net of tax	1.3
Other comprehensive loss, net of tax					1.3
Treasury Stock, Value, Acquired, Cost Method	(20.0)					(20.0)
Stock-based compensation expense	7.4		7.4
Common stock issued for exercise of stock options and other	2.1		2.1
Balance at Jun. 30, 2021	1,332.1	$ 0.9	$ 1,610.2	$ (138.4)	$ (104.4)	$ (36.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(0.1)
Treasury Stock, Value	$ 36.2