STOCK-BASED COMPENSATION (Details) (USD $)	12 Months Ended											12 Months Ended					12 Months Ended						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Options	Dec. 31, 2011 Options	Dec. 31, 2010 Options	Dec. 31, 2009 Options	Dec. 31, 2012 Restricted stock and restricted stock unit	Dec. 31, 2011 Restricted stock and restricted stock unit	Dec. 31, 2010 Restricted stock and restricted stock unit	Dec. 31, 2009 Restricted stock and restricted stock unit	Dec. 31, 2012 2000 Option Plan	Dec. 31, 2012 2000 Option Plan Maximum	Dec. 31, 2012 2000 Option Plan Minimum	Dec. 31, 2012 2000 Option Plan Options	Dec. 31, 2012 2000 Option Plan Restricted stock	Dec. 31, 2010 2000 Purchase Plan	Dec. 31, 2012 2010 Stock Plan	Dec. 31, 2012 2010 Stock Plan Maximum	Dec. 31, 2012 2010 Stock Plan Minimum	Dec. 31, 2012 2010 Stock Plan Options	Dec. 31, 2012 2010 Stock Plan Restricted stock	Dec. 31, 2012 2010 Purchase Plan	Dec. 31, 2011 2010 Purchase Plan	Dec. 31, 2010 2010 Purchase Plan	Dec. 31, 2012 2010 Purchase Plan April 30, 2012	Dec. 31, 2012 2010 Purchase Plan October 31, 2012	Dec. 31, 2012 2010 Purchase Plan Maximum	Dec. 31, 2012 2010 Purchase Plan Minimum item
Stock-based compensation
Expiration period from the date of grant															10 years						10 years
Vesting period	1 year												4 years	3 years					4 years	3 years
Period by which all options to purchase common stock will accelerate upon an acquisition of the company												1 year						1 year
Period from the completion of acquisition, during which if an employee is terminated without cause or for good reason, all awards then outstanding held by that employee will immediately become exercisable																		1 year
Shares outstanding				6,181,996	6,453,644	6,217,199	5,912,019								4,889,933	54,000					1,292,063	759,955
Shares unreleased								813,955	401,490	263,630	40,000
Number of hours per week of customary employment required to participate in the plan																													20
Number of months of customary employment required to participate in the plan																													5 months
Percentage of employee's compensation to be deducted from the employee's pay																												15.00%	1.00%
Option exercise price, expressed as a percentage of fair market value																							85.00%
Maximum value of shares that an employee is permitted to purchase																							$ 25,000
Number of Shares																	58,709						63,611	51,857	115,468	34,336	29,275
Weighted Average Price per Share (in dollars per share)																										$ 5.67	$ 5.89
Shares available for future grant	1,674,450																	1,489,918					184,532
Proceeds from stock option exercise	$ 2,400,000	$ 700,000	$ 500,000														$ 100,000						$ 400,000	$ 300,000