CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2018			$ 1,578.1	$ (242.4)	$ (5.3)	$ (33.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise or redemption of share-based awards			5.2
Stock-based compensation expense			8.8
Net income (loss)	$ (39.8)			(39.8)
Purchases of treasury stock					(3.4)
Other comprehensive income (loss), net of tax						(1.1)
Ending balance at Sep. 30, 2019	1,266.9	$ 0.5	1,592.1	(282.2)	(8.7)	(34.8)
Beginning balance at Jun. 30, 2019			1,586.8	(270.7)	(8.6)	(31.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise or redemption of share-based awards			2.5
Stock-based compensation expense			2.8
Net income (loss)	(11.5)			(11.5)
Purchases of treasury stock					(0.1)
Other comprehensive income (loss), net of tax						(3.7)
Ending balance at Sep. 30, 2019	1,266.9	0.5	1,592.1	(282.2)	(8.7)	(34.8)
Beginning balance at Dec. 31, 2019	1,265.2		1,593.9	(288.3)	(8.9)	(32.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise or redemption of share-based awards			1.3
Stock-based compensation expense			8.9
Net income (loss)	20.0			20.0
Purchases of treasury stock					(0.4)
Other comprehensive income (loss), net of tax						(5.1)
Ending balance at Sep. 30, 2020	1,289.9	0.5	1,604.1	(268.3)	(9.3)	(37.1)
Beginning balance at Jun. 30, 2020			1,599.9	(287.6)	(9.2)	(42.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise or redemption of share-based awards			0.8
Stock-based compensation expense			3.4
Net income (loss)	19.3			19.3
Purchases of treasury stock					(0.1)
Other comprehensive income (loss), net of tax						4.9
Ending balance at Sep. 30, 2020	$ 1,289.9	$ 0.5	$ 1,604.1	$ (268.3)	$ (9.3)	$ (37.1)