STOCKHOLDERS' EQUITY AND SHARE-BASED COMPENSATION EXPENSE - Stock Options Plan Activity (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Options, Outstanding [Roll Forward]
Outstanding at beginning of the period (in shares)	5,142
Grants (in shares)	523
Exercises (in shares)	(742)
Forfeitures or expirations (in shares)	(728)
Outstanding at end of the period (in shares)	4,195
Exercisable (in shares)	2,597
Vested and expected to vest (in shares)	3,982
Weighted Average Exercise Price Per Share [Roll Forward]
Outstanding at beginning of the period (in dollars per share)	$ 6.75
Grants (in dollars per share)	$ 7.98
Exercises (in dollars per share)	$ 4.80
Forfeitures or expirations (in dollars per share)	$ 12.62
Outstanding at end of the period (in dollars per share)	$ 6.23
Exercisable (in dollars per share)	$ 6.58
Vested and expected to vest (in dollars per share)	$ 6.22
Weighted-Average Remaining Contractual Terms [Abstract]
Outstanding at end of the period	3 years 7 months 10 days
Exercisable	2 years 7 months 6 days
Vested and expected to vest	3 years 6 months 0 days
Aggregate Intrinsic Value [Abstract]
Outstanding at end of the period	$ 16,536
Exercisable	9,793
Vested and expected to vest	$ 15,792