Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Nov. 30, 2018	Nov. 30, 2017	Nov. 30, 2018	Nov. 30, 2017	Feb. 28, 2018
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 207,090		$ 207,090		$ 216,855
Operations and assets by segment
Net sales	239,516	$ 208,158	724,539	$ 609,770
Operating Income	22,769	1,554	63,570	38,964
Assets	1,032,379		1,032,379		1,028,209
Energy
Operations and assets by segment
Net sales	132,025	107,021	385,526	317,526
Operating Income	11,532	(12,103)	25,763	(3,029)
Assets	585,807		585,807		554,866
Metal Coatings
Operations and assets by segment
Net sales	107,491	101,137	339,013	292,244
Operating Income	18,321	21,681	65,581	66,332
Assets	436,873		436,873		460,575
Corporate
Operations and assets by segment
Operating Income	(7,084)	(8,024)	(27,774)	(24,339)
Corporate
Operations and assets by segment
Assets	9,699		9,699		12,768
UNITED STATES
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	186,696		186,696		194,418
Operations and assets by segment
Net sales	203,788	175,803	605,672	505,023
CANADA
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	16,619		16,619		18,254
Other Countries [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	3,775		3,775		$ 4,183
International [Member]
Operations and assets by segment
Net sales	$ 35,728	$ 32,355	$ 118,867	$ 104,747