Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets Parenthetical
Allowances on accounts receivable	$ 929,334	$ 1,723,679
Accumulated depreciation on Property and equipment	$ 18,652,300	$ 17,797,835
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	2,000,000	2,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	55,304,402	54,931,397
Common stock, shares outstanding	47,299,167	46,926,162
Common Stock held in treasury, shares	8,005,235	8,005,235