Condensed Consolidated Statements Of Income And Comprehensive Income (Loss) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements Of Income And Comprehensive Income (Loss) [Abstract]
Sales from operations	$ 41,984,570	$ 33,323,793	$ 118,437,057	$ 89,864,628
Costs and expenses:
Cost of sales	25,429,300	18,013,809	70,097,713	50,755,575
Selling, general and administrative expenses	10,071,408	9,005,699	29,189,378	26,492,580
Goodwill impairment	0	0	1,271,986	0
Total costs and expenses	35,500,708	27,019,508	100,559,077	77,248,155
Operating income	6,483,862	6,304,285	17,877,980	12,616,473
Other income and (expenses):
Investment and other income	138,990	92,363	275,852	177,788
Gain (loss) on sale of assets	5,310	9,763	(4,674)	1,143
Interest and other expense	(53,256)	(51,854)	(149,107)	(160,305)
Other income, net	91,044	50,272	122,071	18,626
Income before income taxes	6,574,906	6,354,557	18,000,051	12,635,099
Income tax expense	2,845,269	2,355,163	7,627,910	4,889,452
Net income	3,729,637	3,999,394	10,372,141	7,745,647
Other comprehensive income (loss), net of tax:
Additional minimum pension liability adjustments	(8,534)	(17,009)	(26,952)	(30,590)
Unrealized gains (losses) on available-for-sale securities	(5,094)	11,779	(30,510)	13,259
Foreign currency translation adjustment	(112,581)	149,786	(44,480)	(60,059)
Total other comprehensive income (loss), net of tax	(126,209)	144,556	(101,942)	(77,390)
Comprehensive net income	$ 3,603,428	$ 4,143,950	$ 10,270,199	$ 7,668,257
Basic net income per share:	$ 0.44	$ 0.48	$ 1.23	$ 0.92
Diluted net income per share:	$ 0.44	$ 0.48	$ 1.22	$ 0.92
Average Basic Shares Outstanding	8,460,625	8,398,496	8,442,812	8,376,542
Average Dilutive Shares Outstanding	8,530,187	8,414,865	8,500,022	8,401,212
Dividends per share	$ 0.15	$ 0.15	$ 0.45	$ 0.44