STOCKHOLDERS' EQUTIY AND SHARE-BASED COMPENSATION EXPENSE - Summary of outstanding and exercisable options (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options Outstanding (in shares)	4,195
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	3 years 7 months 10 days
Option Outstanding, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 6.23
Number of Option Exercisable (in shares)	2,597
Option Exercisable, Weighted-Average Exercise Price Per Share (in dollars per share)		$ 6.58
Range $2.70 - 3.91 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range Exercise Price, Lower Range Limit (in dollars per share)	$ 2.7
Range of Exercise Price, Upper Range Limit (in dollars per share)	$ 3.91
Number of Options Outstanding (in shares)	1,126
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	4 years 4 months 10 days
Option Outstanding, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 3.71
Number of Option Exercisable (in shares)	508
Option Exercisable, Weighted-Average Exercise Price Per Share (in dollars per share)		$ 3.60
Range $4.16 - 5.29 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range Exercise Price, Lower Range Limit (in dollars per share)	$ 4.16
Range of Exercise Price, Upper Range Limit (in dollars per share)	$ 5.29
Number of Options Outstanding (in shares)	928
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	3 years 3 months 5 days
Option Outstanding, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 4.55
Number of Option Exercisable (in shares)	744
Option Exercisable, Weighted-Average Exercise Price Per Share (in dollars per share)		$ 4.56
Range $5.31 - 6.71 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range Exercise Price, Lower Range Limit (in dollars per share)	$ 5.31
Range of Exercise Price, Upper Range Limit (in dollars per share)	$ 6.71
Number of Options Outstanding (in shares)	847
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	3 years 6 months 23 days
Option Outstanding, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 6.09
Number of Option Exercisable (in shares)	593
Option Exercisable, Weighted-Average Exercise Price Per Share (in dollars per share)		$ 6.12
Range $7.05 - 10.29 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range Exercise Price, Lower Range Limit (in dollars per share)	$ 7.05
Range of Exercise Price, Upper Range Limit (in dollars per share)	$ 10.29
Number of Options Outstanding (in shares)	1,178
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	3 years 5 months 23 days
Option Outstanding, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 8.77
Number of Option Exercisable (in shares)	636
Option Exercisable, Weighted-Average Exercise Price Per Share (in dollars per share)		$ 9.45
Range $10.52 - 37.22 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range Exercise Price, Lower Range Limit (in dollars per share)	$ 10.52
Range of Exercise Price, Upper Range Limit (in dollars per share)	$ 37.22
Number of Options Outstanding (in shares)	116
Options Outstanding, Weighted-Average Remaining Contractual Life (in years)	0 years 9 months 23 days
Option Outstanding, Weighted-Average Exercise Price Per Share (in dollars per share)	$ 19.34
Number of Option Exercisable (in shares)	116
Option Exercisable, Weighted-Average Exercise Price Per Share (in dollars per share)		$ 19.34