Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Statement of Financial Position [Abstract]
Allowances on accounts receivable	$ 1,723,679	$ 3,242,458
Accumulated depreciation on Property and equipment	$ 17,797,835	$ 19,468,420
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	54,931,397	54,147,234
Common stock, shares outstanding	46,926,162	46,141,999
Common Stock held in treasury, shares	8,005,235	8,005,235