STOCK PLANS AND SHARE-BASED COMPENSATION (Details) (USD $)	3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended						1 Months Ended
	Jun. 30, 2012	Jun. 30, 2012 plans	Jun. 30, 2012 Stock Options [Member]	Jun. 30, 2011 Stock Options [Member]	Jun. 30, 2012 Stock Options [Member]	Jun. 30, 2011 Stock Options [Member]	Jun. 30, 2012 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2011 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2012 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2011 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2012 1997 Employees Stock Purchase Plan [Member]	Jun. 30, 2011 1997 Employees Stock Purchase Plan [Member]	Jun. 30, 2012 1997 Employees Stock Purchase Plan [Member] purchaseperiods	Jun. 30, 2011 1997 Employees Stock Purchase Plan [Member]	Jun. 30, 2012 Performance-based Awards [Member]	Jun. 30, 2011 Performance-based Awards [Member]	Jun. 30, 2012 Performance-based Awards [Member]	Jun. 30, 2011 Performance-based Awards [Member]	Jun. 30, 2012 2007 Equity Incentive Plan [Member]	Jun. 30, 2012 2007 Equity Incentive Plan [Member] Incentive Stock Options [Member]	Jun. 30, 2012 2007 Equity Incentive Plan [Member] Nonstatutory Stock Options [Member]	Jun. 30, 2012 Directors Equity Compensation Program [Member]	Jul. 31, 2012 Revised Directors Equity Compensation Program [Member] Directors Equity Compensation Program [Member]	Jul. 31, 2012 Revised Directors Equity Compensation Program [Member] Directors Equity Compensation Program [Member] Stock Options [Member]	Jul. 31, 2012 Revised Directors Equity Compensation Program [Member] Directors Equity Compensation Program [Member] Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional Shares Authorized	2,800,000
Number of shares available for future issuance	8,730,621	8,730,621									587,964		587,964
Vesting period					4 years				4 years										48 months			3 years
Exercise price of stock options as percentage of fair market value on date of grant, minimum																				100.00%	100.00%
Multiplier for calculation of common stock options granted to directors on the first trading day of the month following commencement of service																						8,000
Number of options granted to directors on the first trading day of July following commencement of service																						24,000
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost			$ 900,000	$ 900,000	$ 1,900,000	$ 2,100,000	$ 1,700,000	$ 900,000	$ 3,100,000	$ 1,400,000	$ 300,000	$ 200,000	$ 600,000	$ 600,000	$ 700,000	$ 300,000	$ 1,100,000	$ 700,000					$ 100,000
Factor used to determine the number of options/units to be purchased																								$ 100,000	$ 100,000
Maximum percentage of employee's compensation eligible for payroll deductions											15.00%		15.00%
Purchase price of the purchase plan as percentage of the lower of the fair market value on the first day of each offering period or on the purchase date													85.00%
Shares reserved for issuance											3,000,000		3,000,000
Number of shares purchased													2,412,036
Number of stock-based compensation plans		2
Awards expiration period, maximum (in years)																			10 years
Number of purchase period in each offering period													1
Duration of each purchase period in each offering period													6 months