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			1 Months Ended	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 plans	Jun. 30, 2012	Jun. 30, 2013 2007 Equity Incentive Plan [Member]	Jun. 30, 2013 Directors Equity Compensation Program [Member]	Jun. 30, 2013 Employee Stock [Member]	Jun. 30, 2012 Employee Stock [Member]	Jun. 30, 2013 Employee Stock [Member] purchaseperiods	Jun. 30, 2012 Employee Stock [Member]	Jun. 30, 2013 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2012 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2013 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2012 Restricted Stock Units (RSUs) [Member]	Dec. 31, 2012 Restricted Stock Units (RSUs) [Member]	Jul. 31, 2012 Restricted Stock Units (RSUs) [Member] Directors Equity Compensation Program [Member]	Jun. 30, 2013 Performance Based Awards [Member]	Jun. 30, 2012 Performance Based Awards [Member]	Jun. 30, 2013 Performance Based Awards [Member]	Jun. 30, 2012 Performance Based Awards [Member]	Dec. 31, 2012 Performance Based Awards [Member]	Jun. 30, 2013 Stock Options [Member]	Jun. 30, 2012 Stock Options [Member]	Jun. 30, 2013 Stock Options [Member]	Jun. 30, 2012 Stock Options [Member]	Jul. 31, 2012 Stock Options [Member] Directors Equity Compensation Program [Member]	Jun. 30, 2013 Incentive Stock Options [Member] 2007 Equity Incentive Plan [Member]	Jul. 31, 2012 Stock Options and Restricted Stock Units (RSUs) [Member] Directors Equity Compensation Program [Member]	Jun. 30, 2013 Nonstatutory Stock Options [Member] 2007 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance	7,706,590		7,706,590
Vesting period					48 months	3 years							4 years											4 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
Allocated Share-based Compensation Expense	$ 4,328,000	$ 3,642,000	$ 7,964,000	$ 6,673,000			$ 300,000	$ 300,000	$ 600,000	$ 600,000	$ 2,400,000	$ 1,700,000	$ 4,400,000	$ 3,100,000			$ 900,000	$ 700,000	$ 1,300,000	$ 1,100,000		$ 700,000	$ 900,000	$ 1,700,000	$ 1,900,000
Factor used to determine the number of options/units to be granted																$ 100,000										$ 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
Share-based Compensation Arrangement by Share-based Payment Award, Employee Shares Purchased for Award							2,541,673		2,541,673
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant							458,327		458,327
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
Number of performance-based awards shares released as percentage of target number, minimum																			0.00%
Number of performance-based awards shares released as percentage of target number, maximum																			200.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period													176,000						54,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number											715,000		715,000		573,000		99,000		99,000		102,000