Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2016	Nov. 30, 2015	Feb. 29, 2016
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 224,092		$ 224,092		$ 226,333
Operations and assets by segment
Net Sales	227,459	$ 242,447	665,171	$ 685,581
Operating Income	28,784	36,408	78,182	95,712
Interest Expense	3,654	3,743	11,159	11,612
Gain (Loss) on Disposition of Property Plant Equipment	(57)	(16)	26	(465)
Other Nonoperating Income (Expense)	(759)	(27)	(949)	828
Income Before Income Taxes	25,946	32,708	67,946	83,737
Assets	1,017,675	990,952	1,017,675	990,952	982,010
Energy [Member]
Operations and assets by segment
Net Sales	135,553	136,007	371,256	383,787
Operating Income	15,434	18,846	42,383	45,807
Assets	577,328	539,193	577,328	539,193
Galvanizing Services [Member]
Operations and assets by segment
Net Sales	91,906	106,440	293,915	301,794
Operating Income	21,345	24,264	60,679	71,689
Assets	421,991	432,297	421,991	432,297
Corporate, Non-Segment [Member]
Operations and assets by segment
Operating Income	(7,995)	(6,702)	(24,880)	(21,784)
Corporate [Member]
Operations and assets by segment
Assets	18,356	19,462	18,356	19,462
UNITED STATES
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	200,943		200,943		204,587
Operations and assets by segment
Net Sales	191,526	197,372	537,084	543,306
CANADA
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	17,774		17,774		17,868
Other Countries [Member]
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	5,375		5,375		$ 3,878
International [Member]
Operations and assets by segment
Net Sales	35,933	45,424	128,243	142,970
Geography Eliminations [Member]
Operations and assets by segment
Net Sales	$ 0	$ (349)	$ (156)	$ (695)