SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Net Sales	$ 61,116	$ 59,780	$ 60,203	$ 59,582	$ 57,731	$ 55,538	$ 57,201	$ 56,285	$ 240,681	$ 226,755	$ 219,050
Gross Profit	15,543	14,705	14,554	14,203	12,433	11,907	12,492	13,208	59,005	50,040	49,688
Net Income (Loss)	$ (108)	$ 1,892	$ 3,239	$ 1,075	$ 2,895	$ 1,860	$ 1,777	$ 2,519	$ 6,098	$ 9,051	$ 9,458
Net Income (Loss) Per Share, Diluted	$ (0.02)	$ 0.26	$ 0.45	$ 0.15	$ 0.40	$ 0.26	$ 0.25	$ 0.35	$ 0.85	$ 1.26	$ 1.30
Common Stock
Net Income (Loss) Per Share, Basic	$ (0.02)	$ 0.28	$ 0.49	$ 0.16	$ 0.43	$ 0.28	$ 0.27	$ 0.38	$ 0.92	$ 1.36	$ 1.42
Dividends Per Share	$ 0.1800	$ 0.1700	$ 0.1700	$ 0.1700	$ 0.1700	$ 0.1600	$ 0.1600	$ 0.1600	$ 0.6900	$ 0.6500
Common Stock Price Range, High	$ 22.39	$ 22.44	$ 21.61	$ 21.00	$ 22.39	$ 22.17	$ 23.00	$ 22.20
Common Stock Price Range, Low	$ 18.29	$ 19.39	$ 19.00	$ 16.87	$ 19.11	$ 18.74	$ 18.81	$ 18.73
Common Class B
Net Income (Loss) Per Share, Basic	$ (0.01)	$ 0.21	$ 0.36	$ 0.12	$ 0.33	$ 0.22	$ 0.20	$ 0.30	$ 0.70	$ 1.06	$ 1.07
Dividends Per Share	$ 0.1350	$ 0.1275	$ 0.1275	$ 0.1275	$ 0.1275	$ 0.1200	$ 0.1200	$ 0.1200	$ 0.5175	$ 0.4875