Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	May 31, 2017	May 31, 2016	Feb. 28, 2017
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 230,127		$ 228,610
Operations and assets by segment
Net Sales	208,551	$ 242,667
Operating Income	21,907	34,508
Interest Expense	3,360	3,925
Gain (Loss) on Disposition of Property Plant Equipment	(100)	(110)
Other Nonoperating Income (Expense)	(85)	(122)
Income Before Income Taxes	18,732	30,815
Assets	1,004,998	1,010,608	977,839
Energy [Member]
Operations and assets by segment
Net Sales	116,474	138,102
Operating Income	8,595	18,753
Assets	558,381	553,580
Galvanizing Services [Member]
Operations and assets by segment
Net Sales	92,077	104,565
Operating Income	21,242	24,302
Assets	432,516	433,634
Corporate, Non-Segment [Member]
Operations and assets by segment
Operating Income	(7,930)	(8,547)
Corporate [Member]
Operations and assets by segment
Assets	14,101	23,394
UNITED STATES
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	207,149		205,079
Operations and assets by segment
Net Sales	169,998	188,660
CANADA
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	17,369		18,002
Other Countries [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	5,609		$ 5,529
International [Member]
Operations and assets by segment
Net Sales	38,553	54,163
Geography Eliminations [Member]
Operations and assets by segment
Net Sales	$ 0	$ (156)