Consolidated Statements of Earnings (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2012	Aug. 31, 2011
Consolidated Statements of Earnings [Abstract]
Net sales	$ 138,344	$ 130,384	$ 280,872	$ 273,642
Cost of goods sold	104,395	96,290	218,674	199,847
Gross profit margin	33,949	34,094	62,198	73,795
Selling, general and administrative	21,331	18,447	43,357	39,304
Gain from disposal of assets	(5)	(125)	(9)	(125)
Income from operations	12,623	15,772	18,850	34,616
Other income (expense)
Interest expense	(402)	(664)	(871)	(1,482)
Other, net	(265)	171	85	(5)
Total other income (expense)	(667)	(493)	(786)	(1,487)
Earnings before income taxes	11,956	15,279	18,064	33,129
Provision for income taxes	4,364	5,567	6,593	11,993
Net earnings	$ 7,592	$ 9,712	$ 11,471	$ 21,136
Weighted average common shares outstanding
Basic	25,992,505	25,933,902	25,984,188	25,914,986
Diluted	26,011,143	25,961,171	26,003,583	25,943,361
Per share amounts
Net earnings - basic	$ 0.29	$ 0.37	$ 0.44	$ 0.82
Net earnings - diluted	$ 0.29	$ 0.37	$ 0.44	$ 0.81
Cash dividends per share	$ 0.175	$ 0.155	$ 0.350	$ 0.310