Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2018	Aug. 31, 2017	Feb. 28, 2018
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 209,404		$ 209,404		$ 216,855
Operations and assets by segment
Net sales	222,787	$ 196,329	485,023	$ 401,612
Operating Income	17,105	17,387	40,801	37,410
Assets	1,038,024		1,038,024		1,028,209
Energy
Operations and assets by segment
Net sales	106,515	97,299	253,501	210,504
Operating Income	4,273	2,363	14,231	9,074
Assets	574,230		574,230		554,866
Metal Coatings
Operations and assets by segment
Net sales	116,272	99,030	231,522	191,108
Operating Income	22,076	23,409	47,260	44,651
Assets	453,821		453,821		460,575
Corporate
Operations and assets by segment
Operating Income	(9,244)	(8,385)	(20,690)	(16,315)
Corporate
Operations and assets by segment
Assets	9,973		9,973		12,768
UNITED STATES
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	187,983		187,983		194,418
Operations and assets by segment
Net sales	188,278	162,490	401,834	329,219
CANADA
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	17,410		17,410		18,254
Other Countries [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	4,011		4,011		$ 4,183
International [Member]
Operations and assets by segment
Net sales	$ 34,509	$ 33,839	$ 83,189	$ 72,393