Condensed Consolidated Statements of Stockholders' Deficit (Unaudited) - USD ($) $ in Millions	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Total
Beginning balance, value at Dec. 31, 2019		$ 320.6	$ 45.1	$ (425.0)	$ (59.3)
Beginning balance, shares at Dec. 31, 2019	22,230,768
Foreign currency translation adjustments			3.1		3.1
Actuarial losses on pension plan			4.4		4.4
Change in fair value of hedging instrument			(1.5)		(1.5)
Reclassification of loss on hedging instrument to comprehensive income			0.4		0.4
Shares issued in net settlement of RSUs
Shares issued upon net settlement of RSUs, shares	166,959
Stock-based compensation expense - ESPP, shares	7,649
Stock-based compensation expense		1.0			1.0
Net loss				(9.8)	(9.8)
Ending balance, value at Mar. 31, 2020		321.6	51.5	(434.8)	(61.7)
Ending balance, shares at Mar. 31, 2020	22,397,727
Beginning balance, value at Dec. 31, 2019		320.6	45.1	(425.0)	(59.3)
Beginning balance, shares at Dec. 31, 2019	22,230,768
Foreign currency translation adjustments					3.5
Change in fair value of hedging instrument					(2.3)
Net loss					(36.0)
Ending balance, value at Jun. 30, 2020		322.6	42.7	(461.0)	(95.7)
Ending balance, shares at Jun. 30, 2020	22,405,376
Beginning balance, value at Mar. 31, 2020		321.6	51.5	(434.8)	(61.7)
Beginning balance, shares at Mar. 31, 2020	22,397,727
Foreign currency translation adjustments			0.4		0.4
Actuarial losses on pension plan			(8.7)		(8.7)
Change in fair value of hedging instrument			(0.8)		(0.8)
Reclassification of loss on hedging instrument to comprehensive income			0.3		0.3
Stock-based compensation expense – ESPP
Stock-based compensation expense		1.0			1.0
Net loss				(26.2)	(26.2)
Ending balance, value at Jun. 30, 2020		322.6	42.7	(461.0)	(95.7)
Ending balance, shares at Jun. 30, 2020	22,405,376
Beginning balance, value at Dec. 31, 2020		324.6	31.1	(457.4)	(101.7)
Beginning balance, shares at Dec. 31, 2020	22,430,475
Foreign currency translation adjustments			(1.1)		(1.1)
Actuarial losses on pension plan			4.6		4.6
Change in fair value of hedging instrument			0.6		0.6
Reclassification of loss on hedging instrument to comprehensive income			0.5		0.5
Shares issued in net settlement of RSUs
Shares issued upon net settlement of RSUs, shares	163,732
Stock-based compensation expense		1.4			1.4
Net loss				(16.7)	(16.7)
Ending balance, value at Mar. 31, 2021		326.0	35.7	(474.1)	(112.4)
Ending balance, shares at Mar. 31, 2021	22,594,207
Beginning balance, value at Dec. 31, 2020		324.6	31.1	(457.4)	(101.7)
Beginning balance, shares at Dec. 31, 2020	22,430,475
Foreign currency translation adjustments					(1.0)
Change in fair value of hedging instrument					0.3
Net loss					(60.5)
Ending balance, value at Jun. 30, 2021		329.3	36.9	(517.9)	(151.7)
Ending balance, shares at Jun. 30, 2021	22,594,207
Beginning balance, value at Mar. 31, 2021		326.0	35.7	(474.1)	(112.4)
Beginning balance, shares at Mar. 31, 2021	22,594,207
Foreign currency translation adjustments			0.1		0.1
Actuarial losses on pension plan			0.9		0.9
Change in fair value of hedging instrument			(0.3)		(0.3)
Reclassification of loss on hedging instrument to comprehensive income			0.5		0.5
Stock-based compensation expense		3.3			3.3
Net loss				(43.8)	(43.8)
Ending balance, value at Jun. 30, 2021		$ 329.3	$ 36.9	$ (517.9)	$ (151.7)
Ending balance, shares at Jun. 30, 2021	22,594,207