EQUITY INCENTIVE PLANS - Summary of options outstanding (Details 1) (Equity Incentive Plan, Stock Options, USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2012	7,157,458	6,547,443	6,355,827	5,215,189
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 1 month 6 days
Options Outstanding, Weighted Average Exercise Price	$ 5.70	$ 5.34	$ 5.29	$ 6.04
Options Exercisable as of December 31, 2012	4,428,151
Options Exercisable, Weighted Average Exercise Price	$ 5.17
Range of Exercise Prices : $ 2.35 - 2.80
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2012	18,000
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 10 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 2.48
Options Exercisable as of December 31, 2012	17,000
Options Exercisable, Weighted Average Exercise Price	$ 2.46
Range of Exercise Prices, Lower Limit	$ 2.35
Range of Exercise Prices, Upper Limit	$ 2.80
Range of Exercise Prices : $ 2.80 - 5.60
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2012	2,859,287
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 4 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 3.92
Options Exercisable as of December 31, 2012	2,319,636
Options Exercisable, Weighted Average Exercise Price	$ 4.01
Range of Exercise Prices, Lower Limit	$ 2.80
Range of Exercise Prices, Upper Limit	$ 5.60
Range of Exercise Prices : $ 5.60 - 8.40
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2012	4,203,171
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 7 months 6 days
Options Outstanding, Weighted Average Exercise Price	$ 6.86
Options Exercisable as of December 31, 2012	2,014,515
Options Exercisable, Weighted Average Exercise Price	$ 6.39
Range of Exercise Prices, Lower Limit	$ 5.60
Range of Exercise Prices, Upper Limit	$ 8.40
Range of Exercise Prices : $ 8.40 - 11.20
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2012	77,000
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 4 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 9.09
Options Exercisable as of December 31, 2012	77,000
Options Exercisable, Weighted Average Exercise Price	$ 9.09
Range of Exercise Prices, Lower Limit	$ 8.40
Range of Exercise Prices, Upper Limit	$ 11.20