Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	May 31, 2018	May 31, 2017	Feb. 28, 2018
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 214,341		$ 216,855
Operations and assets by segment
Net sales	262,236	$ 205,283
Operating Income	23,696	20,023
Assets	1,070,184		1,028,209
Energy
Operations and assets by segment
Net sales	146,986	113,206
Operating Income	9,958	6,711
Assets	597,143		554,866
Metal Coatings
Operations and assets by segment
Net sales	115,250	92,077
Operating Income	25,184	21,242
Assets	459,708		460,575
Corporate
Operations and assets by segment
Operating Income	(11,446)	(7,930)
Corporate
Operations and assets by segment
Assets	13,333		12,768
UNITED STATES
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	192,748		194,418
Operations and assets by segment
Net sales	213,606	166,730
CANADA
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	17,574		18,254
Other Countries [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	4,019		$ 4,183
International [Member]
Operations and assets by segment
Net sales	48,630	38,553
Geography Eliminations [Member]
Operations and assets by segment
Net sales		$ 0