EMPLOYEE STOCK PLANS - Summary of Stock Option Activity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Number of Shares
Outstanding, beginning balance (in shares)	4,993,000	7,614,000
Granted (in shares)	700,000	1,600,000	3,100,000
Exercised (in shares)	(486,000)	(405,000)
Forfeited or expired (in shares)	(333,000)	(3,795,000)
Outstanding, ending balance (in shares)	4,920,000	4,993,000	7,614,000
Vested and expected to vest (in shares)	4,586,000
Exercisable (in shares)	3,175,000
Weighted-Average Exercise Price
Weighted-Average Exercise Price Per Share, beginning balance (in usd per share)	$ 2.18	$ 3.34
Weighted Average Exercise Price Per Share, Granted (in usd per share)	$ 2.42	$ 1.40
Weighted Average Exercise Price Per Share, Exercised (in usd per share)	$ 1.03	$ 1.10
Weighted Average Exercise Price Per Share, Forfeited or expired (in usd per share)	$ 7.01	$ 4.29
Weighted-Average Exercise Price Per Share, ending balance (in usd per share)	$ 2.01	$ 2.18	$ 3.34
Weighted Average Exercise Price, Vested and expected to vest (in usd per share)	$ 2.01
Weighted Average Exercise Price, Exercisable (in usd per share)	$ 2.06
Weighted Average Remaining Term
Weighted Average Remaining Contractual Life	4 years 2 months 12 days	4 years 10 months 24 days
Weighted Average Remaining Contractual Life, Vested and expected to vest	4 years 1 month 6 days
Weighted Average Remaining Contractual Life, Exercisable	3 years 7 months 6 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 7,513	$ 5,281
Aggregate Intrinsic Value, Vested and expected to vest	7,040
Aggregate Intrinsic Value, Exercisable	$ 4,907