Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended		6 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]
Net sales	$ 8,052,447	$ 8,265,754	$ 15,944,324	$ 16,259,681
Cost of sales	5,907,939	6,083,894	11,317,623	12,076,013
Gross profit	2,144,508	2,181,860	4,626,701	4,183,668
Selling, general and administrative expenses	687,108	690,825	1,409,697	1,433,692
Operating income	1,457,400	1,491,035	3,217,004	2,749,976
Other income
Interest and dividend income	7,510	13,303	18,415	23,470
Other	9,656	(10,781)	14,505	16,102
Total other income	17,166	2,522	32,920	39,572
Income before income taxes	1,474,566	1,493,557	3,249,924	2,789,548
Provision for income taxes	402,790	422,694	897,430	791,781
Net income	1,071,776	1,070,863	2,352,494	1,997,767
Other comprehensive income, net of tax:
Unrealized gain on investment securities	1,422	1,854	1,705	162
Total comprehensive income	$ 1,073,198	$ 1,072,717	$ 2,354,199	$ 1,997,929
Net income per share:
Basic	$ 0.49	$ 0.49	$ 1.07	$ 0.92
Diluted	$ 0.48	$ 0.49	$ 1.05	$ 0.91
Weighted average number of shares outstanding:
Basic	2,201,140	2,172,601	2,193,782	2,168,401
Diluted	2,238,745	2,200,633	2,236,553	2,198,368
Dividends per share:	$ 1.25	$ 1.225	$ 1.475	$ 1.45