Condensed Consolidated Statements of Stockholders’ Deficit (Unaudited) - USD ($) $ in Millions	Common stock	Additional paid in capital	Accumulated other comprehensive income	Accumulated deficit	Total
Balance at Sep. 30, 2017		$ 323.5	$ 53.1	$ (378.9)	$ (2.3)
Balance, shares at Sep. 30, 2017	20,402,602
Foreign currency translation adjustments			0.1		0.1
Actuarial losses on pension plan			(2.0)		(2.0)
Change in fair value of hedging instrument
Shares issued on exercise of warrants
Shares issued on exercise of warrants, shares	50
Shares issued upon cashless exercise of RSUs		(1.1)			(1.1)
Shares issued upon cashless exercise of RSUs, shares	445,723
Stock-based compensation expense		0.8			0.8
Reclassification of RSUs to derivative liability due to modification		(1.5)			(1.5)
Net loss				(4.2)	(4.2)
Balance at Dec. 31, 2017		321.7	51.2	(383.1)	(10.2)
Balance, shares at Dec. 31, 2017	20,848,375
Foreign currency translation adjustments			0.3		0.3
Actuarial losses on pension plan			1.3		1.3
Shares issued upon cashless exercise of RSUs
Shares issued upon cashless exercise of RSUs, shares	12,216
Stock-based compensation expense		1.0			1.0
Reclassification of RSUs from derivative liability due to stockholder approval of equity plan		2.8			2.8
Net loss				(0.5)	(0.5)
Balance at Mar. 31, 2018		325.5	52.8	(383.6)	(5.3)
Balance, shares at Mar. 31, 2018	20,860,591
Balance at Dec. 31, 2017		321.7	51.2	(383.1)	(10.2)
Balance, shares at Dec. 31, 2017	20,848,375
Foreign currency translation adjustments					0.1
Actuarial losses on pension plan					4.3
Change in fair value of hedging instrument
Reclassification of gain on hedging instrument to comprehensive income
Net loss					(4.5)
Balance at Jun. 30, 2018		327.0	55.6	(387.6)	(5.0)
Balance, shares at Jun. 30, 2018	20,860,591
Balance at Mar. 31, 2018		325.5	52.8	(383.6)	(5.3)
Balance, shares at Mar. 31, 2018	20,860,591
Foreign currency translation adjustments			(0.2)		(0.2)
Actuarial losses on pension plan			3.0		3.0
Stock-based compensation expense		1.5			1.5
Net loss				(4.0)	(4.0)
Balance at Jun. 30, 2018		327.0	55.6	(387.6)	(5.0)
Balance, shares at Jun. 30, 2018	20,860,591
Balance at Sep. 30, 2018		328.5	58.5	(399.5)	$ (12.5)
Balance, shares at Sep. 30, 2018	20,860,591				20,860,591
Foreign currency translation adjustments
Actuarial losses on pension plan			(2.8)		(2.8)
Change in fair value of hedging instrument			2.6		2.6
Reclassification of gain on hedging instrument to comprehensive income			(2.4)		(2.4)
Shares issued upon cashless exercise of RSUs
Shares issued upon cashless exercise of RSUs, shares	9,806
Stock-based compensation expense		1.4			1.4
Net loss				(4.7)	(4.7)
Balance at Dec. 31, 2018		329.9	55.9	(404.2)	(18.4)
Balance, shares at Dec. 31, 2018	20,870,397
Foreign currency translation adjustments			(0.5)		(0.5)
Actuarial losses on pension plan			0.9		0.9
Change in fair value of hedging instrument			(2.1)		(2.1)
Reclassification of gain on hedging instrument to comprehensive income			1.5		1.5
Shares issued on earnout		8.6			8.6
Shares issued on earnout, shares	1,323,558
Stock-based compensation expense		1.7			1.7
Net loss				(5.0)	(5.0)
Balance at Mar. 31, 2019		340.2	55.7	(409.2)	(13.3)
Balance, shares at Mar. 31, 2019	22,193,955
Balance at Dec. 31, 2018		329.9	55.9	(404.2)	(18.4)
Balance, shares at Dec. 31, 2018	20,870,397
Foreign currency translation adjustments					0.2
Actuarial losses on pension plan					(1.1)
Change in fair value of hedging instrument					0.3
Reclassification of gain on hedging instrument to comprehensive income					(1.1)
Net loss					(15.7)
Balance at Jun. 30, 2019		343.1	54.2	(419.9)	$ (22.6)
Balance, shares at Jun. 30, 2019	22,193,955				22,193,955
Balance at Mar. 31, 2019		340.2	55.7	(409.2)	$ (13.3)
Balance, shares at Mar. 31, 2019	22,193,955
Foreign currency translation adjustments			0.7		0.7
Actuarial losses on pension plan			(2.0)		(2.0)
Change in fair value of hedging instrument			2.4		2.4
Reclassification of gain on hedging instrument to comprehensive income			(2.6)		(2.6)
Conversion of awards previously classified as derivatives		0.8			0.8
Stock-based compensation expense		2.1			2.1
Net loss				(10.7)	(10.7)
Balance at Jun. 30, 2019		$ 343.1	$ 54.2	$ (419.9)	$ (22.6)
Balance, shares at Jun. 30, 2019	22,193,955				22,193,955