Stockholders' Equity (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of stock option activity
Number of Shares, Outstanding at beginning of period	4,553,251	4,311,539	3,662,133
Weighted Average Exercise Price Per Share, Outstanding at beginning of period	$ 3.66	$ 3.65	$ 3.78
Aggregate Intrinsic Value, Outstanding at beginning of period		$ 2,671,309
Number of Shares, granted	0	0	0
Number of Shares, Exercised	(789,305)	(129,888)	(31,733)
Weighted average Exercise Price Per Share, Exercised	$ 2.60	$ 2.69	$ 3.08
Number of Shares, Forfeitures	(250,741)	(76,937)	(100,998)
Weighted Average Exercise Price Per Share, Forfeitures	$ 3.26	$ 3.09	$ 3.10
Number of Shares, Outstanding at end of period	4,279,919	4,553,251	4,311,539
Weighted Average Exercise Price Per Share, Outstanding at end of period	$ 3.70	$ 3.66	$ 3.65
Aggregate Intrinsic Value, Outstanding at end of period	$ 4,572,205		$ 2,671,309
Officers and Directors [Member]
Summary of stock option activity
Number of Shares, granted	281,174	209,619	399,661
Weighted Average Exercise Price Per Share, Granted	$ 2.36	$ 3.44	$ 2.68
Others [Member]
Summary of stock option activity
Number of Shares, granted	485,540	238,918	382,476
Weighted Average Exercise Price Per Share, Granted	$ 2.80	$ 3.41	$ 3.22