Variable Interest Entities - Summary of Revenues and Expenses Included in Consolidated Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Nov. 30, 2019	Aug. 31, 2019	May 31, 2019	Nov. 30, 2018	Aug. 31, 2018	May 31, 2018	Nov. 30, 2019	Nov. 30, 2018
Variable Interest Entity [Line Items]
Net sales	$ 110,112			$ 129,637			$ 293,812	$ 339,359
Cost of sales	78,648			90,714			212,570	241,696
Gross profit	31,464			38,923			81,242	97,663
Selling	9,580			10,363			28,162	30,661
General and administrative	16,689			16,482			51,896	49,632
Engineering and technical support	5,059			6,368			15,901	18,349
Total operating expenses	31,328			33,213			95,959	108,456
Operating loss	136			5,710			(14,717)	(10,793)
Interest and bank charges	(751)			(1,174)			(2,635)	(3,391)
Other, net	(322)			260			1,869	1,173
Total other income (expense), net	3,951			781			7,738	(545)
Income (loss) before income taxes	4,087			6,491			(6,979)	(11,338)
Income tax expense	2,720			(4,078)			1,190	3,147
Net income (loss)	1,367	$ (7,164)	$ (2,372)	10,569	$ (22,502)	$ (2,552)	(8,169)	(14,485)
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Net sales	138			331			412	547
Cost of sales	178			23			592	59
Gross profit	(40)			308			(180)	488
Selling	173			301			535	925
General and administrative	1,123			1,202			3,500	3,745
Engineering and technical support	1,232			1,982			3,951	5,600
Total operating expenses	2,528			3,485			7,986	10,270
Operating loss	(2,568)			(3,177)			(8,166)	(9,782)
Interest and bank charges	(324)			(1,032)			(939)	(2,919)
Other, net	79						79
Total other income (expense), net	(245)			(1,032)			(860)	(2,919)
Income (loss) before income taxes	(2,813)			(4,209)			(9,026)	(12,701)
Net income (loss)	$ (2,813)			$ (4,209)			$ (9,026)	$ (12,701)