Variable Interest Entity - 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, 2020	Aug. 31, 2020	May 31, 2020	Nov. 30, 2019	Aug. 31, 2019	May 31, 2019	Nov. 30, 2020	Nov. 30, 2019
Variable Interest Entity [Line Items]
Net sales	$ 201,065			$ 110,112			$ 401,084	$ 293,812
Cost of sales	142,937			78,648			284,905	212,570
Gross profit	58,128			31,464			116,179	81,242
Selling	12,761			9,580			30,190	28,162
General and administrative	21,128			16,689			51,668	51,896
Engineering and technical support	5,676			5,059			14,942	15,901
Total operating expenses	39,565			31,328			96,800	95,959
Operating income (loss)	18,563			136			19,379	(14,717)
Interest and bank charges	(471)			(751)			(2,334)	(2,635)
Other, net	(121)			(322)			21	1,869
Total other income, net	1,211			3,951			2,235	7,738
Income (loss) before income taxes	19,774			4,087			21,614	(6,979)
Income tax expense	2,334			2,720			6,724	1,190
Net income (loss)	17,440	$ 6,555	$ (9,105)	1,367	$ (7,164)	$ (2,372)	14,890	(8,169)
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Net sales	343			138			703	412
Cost of sales	293			178			674	592
Gross profit	50			(40)			29	(180)
Selling	132			173			434	535
General and administrative	446			1,123			1,303	3,500
Engineering and technical support	1,178			1,232			3,427	3,951
Total operating expenses	1,756			2,528			5,164	7,986
Operating income (loss)	(1,706)			(2,568)			(5,135)	(8,166)
Interest and bank charges	(372)			(324)			(1,094)	(939)
Other, net				79				79
Total other income, net	(372)			(245)			(1,094)	(860)
Income (loss) before income taxes	(2,078)			(2,813)			(6,229)	(9,026)
Net income (loss)	$ (2,078)			$ (2,813)			$ (6,229)	$ (9,026)