Segments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Aug. 31, 2015 USD ($)	Aug. 31, 2014 USD ($)	Aug. 31, 2015 USD ($) segment	Aug. 31, 2014 USD ($)	Feb. 28, 2015 USD ($)
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 223,573		$ 223,573		$ 196,583
Number of operating segments | segment			2
Operations and assets by segment
Net Sales	214,246	$ 193,416	$ 443,134	$ 409,542
Operating Income	26,419	22,956	59,304	50,804
Interest Expense	4,023	4,224	7,869	8,432
Gain (Loss) on Disposition of Property Plant Equipment	(25)	3	(449)	(23)
Other Nonoperating Income (Expense)	547	17	855	(14)
Income Before Income Taxes	21,874	18,712	51,029	42,409
Assets	984,047	969,788	984,047	969,788	936,914
Energy [Member]
Operations and assets by segment
Net Sales	110,777	100,560	247,780	231,081
Operating Income	9,005	(1,241)	26,961	12,416
Assets	527,769	530,535	527,769	530,535
Galvanizing Services [Member]
Operations and assets by segment
Net Sales	103,469	92,856	195,354	178,461
Operating Income	25,331	23,059	47,425	45,069
Assets	431,494	387,393	431,494	387,393
Corporate, Non-Segment [Member]
Operations and assets by segment
Operating Income	(7,917)	1,138	(15,082)	(6,681)
Corporate [Member]
Operations and assets by segment
Assets	24,784	51,860	24,784	51,860
UNITED STATES
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	202,515		202,515		173,712
Operations and assets by segment
Net Sales	163,664	142,385	345,934	318,824
CANADA
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	18,260		18,260		20,289
Other Countries [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	2,798		2,798		$ 2,582
International [Member]
Operations and assets by segment
Net Sales	50,928	51,031	97,546	90,718
Geography Eliminations [Member]
Operations and assets by segment
Net Sales	$ (346)	$ 0	$ (346)	$ 0