STOCKHOLDERS' EQUITY AND SHARE-BASED COMPENSATION EXPENSE, Employee Stock Purchase Plan (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserve for issuance under Employee stock purchase plan (in shares)	7,000,000		7,000,000
ESPP purchase consideration as percentage of market value (in hundredths)			85.00%
ESPP offering period			12 months
ESPP number of purchase periods per offering period			2
Number of months in each purchase period			6 months
Look-back period for ESPP			12 months
Percentage of gross compensation through payroll deductions employees can invest (in hundredths)	15.00%		15.00%
Number of shares of common stock employee permitted to purchase (in shares)			750
Number of participants in ESPP	296		296
Total stock-based compensation expense	$ 1,999	$ 2,259	$ 5,109	$ 14,857
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk free interest rate	1.40%	0.60%	1.00%	0.60%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected volatility	68.00%	67.00%	68.00%	67.00%
Expected term (in years)	4 years 7 months 6 days	4 years 7 months 6 days	4 years 7 months 6 days	4 years 7 months 6 days
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 100	$ 100	$ 400	$ 500
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk free interest rate	0.10%	0.10%	0.10%	0.10%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected volatility	52.60%	67.00%	52.60%	67.00%
Expected term (in years)	7 months 24 days	9 months 18 days	7 months 24 days	9 months 18 days