Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	May 31, 2016	May 31, 2015	Feb. 29, 2016
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 230,165	$ 226,333	$ 226,333
Operations and assets by segment
Net Sales	242,667	228,888
Operating Income	34,508	32,885
Interest Expense	3,925	3,847
Gain (Loss) on Disposition of Property Plant Equipment	(110)	(424)
Other Nonoperating Income (Expense)	(122)	307
Income Before Income Taxes	30,815	29,155
Assets	1,010,608	989,365	$ 982,010
Energy [Member]
Operations and assets by segment
Net Sales	138,102	137,003
Operating Income	18,753	17,956
Assets	553,580	556,308
Galvanizing Services [Member]
Operations and assets by segment
Net Sales	104,565	91,885
Operating Income	24,302	22,094
Assets	433,634	374,905
Corporate, Non-Segment [Member]
Operations and assets by segment
Operating Income	(8,547)	(7,165)
Corporate [Member]
Operations and assets by segment
Assets	23,394	58,152
UNITED STATES
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	206,057	204,587
Operations and assets by segment
Net Sales	146,277	182,270
CANADA
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	18,364	17,868
Other Countries [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	5,744	3,878
International [Member]
Operations and assets by segment
Net Sales	96,540	46,618
Geography Eliminations [Member]
Operations and assets by segment
Net Sales	$ (150)	$ 0