Segments (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Nov. 30, 2015 USD ($)	Nov. 30, 2014 USD ($)	Nov. 30, 2015 USD ($) segment	Nov. 30, 2014 USD ($)	Feb. 28, 2015 USD ($)
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 225,428		$ 225,428		$ 196,583
Number of operating segments | segment			2
Operations and assets by segment
Net Sales	242,447	$ 224,833	$ 685,581	$ 634,376
Operating Income	36,408	32,928	95,712	83,732
Interest Expense	3,743	4,099	11,612	12,531
Gain (Loss) on Disposition of Property Plant Equipment	(16)	(1,171)	(465)	(1,195)
Other Nonoperating Income (Expense)	(27)	1,322	828	1,309
Income Before Income Taxes	32,708	28,678	83,737	71,087
Assets	990,952	981,339	990,952	981,339	936,914
Energy [Member]
Operations and assets by segment
Net Sales	136,007	130,052	383,787	361,133
Operating Income	18,846	16,482	45,807	28,898
Assets	539,193	549,968	539,193	549,968
Galvanizing Services [Member]
Operations and assets by segment
Net Sales	106,440	94,781	301,794	273,243
Operating Income	24,264	23,156	71,689	68,225
Assets	432,297	385,217	432,297	385,217
Corporate, Non-Segment [Member]
Operations and assets by segment
Operating Income	(6,702)	(6,710)	(21,784)	(13,391)
Corporate [Member]
Operations and assets by segment
Assets	19,462	46,154	19,462	46,154
UNITED STATES
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	204,758		204,758		173,712
Operations and assets by segment
Net Sales	197,372	177,801	543,306	516,127
CANADA
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	17,889		17,889		20,289
Other Countries [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	2,781		2,781		$ 2,582
International [Member]
Operations and assets by segment
Net Sales	45,424	49,068	142,970	120,285
Geography Eliminations [Member]
Operations and assets by segment
Net Sales	$ (349)	$ (2,036)	$ (695)	$ (2,036)