Consolidated Statements of Earnings (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Nov. 30, 2011	Nov. 30, 2010	Nov. 30, 2011	Nov. 30, 2010
Consolidated Statements of Earnings [Abstract]
Net sales	$ 121,846	$ 134,817	$ 395,488	$ 418,592
Cost of goods sold	91,663	98,298	291,510	300,185
Gross profit margin	30,183	36,519	103,978	118,407
Selling, general and administrative	19,094	20,971	58,398	62,494
Gain from disposal of assets	(8)		(133)
Income from operations	11,097	15,548	45,713	55,913
Other income (expense)
Interest expense	(405)	(214)	(1,887)	(972)
Other, net	318	(148)	313	(119)
Total other income (expense)	(87)	(362)	(1,574)	(1,091)
Earnings before income taxes	11,010	15,186	44,139	54,822
Provision for income taxes	4,118	5,543	16,111	20,010
Net earnings	$ 6,892	$ 9,643	$ 28,028	$ 34,812
Weighted average common shares outstanding
Basic	25,934,972	25,857,544	25,930,484	25,839,289
Diluted	25,954,399	25,907,168	25,955,104	25,884,606
Per share amounts
Net earnings--basic	$ 0.27	$ 0.37	$ 1.08	$ 1.35
Net earnings--diluted	$ 0.27	$ 0.37	$ 1.08	$ 1.34
Cash dividends per share	$ 0.155	$ 0.155	$ 0.465	$ 0.465