STOCK-BASED COMPENSATION (Details) (USD $) In Thousands, except Share data, unless otherwise specified				3 Months Ended		3 Months Ended	12 Months Ended	3 Months Ended
	Mar. 31, 2013	Mar. 28, 2013	Nov. 06, 2009	Mar. 31, 2013 ESPP item	Nov. 09, 2010 ESPP	Mar. 31, 2013 Stock options	Dec. 31, 2012 Stock options	Mar. 31, 2013 Stock options Minimum	Mar. 31, 2013 Stock options Maximum	Mar. 31, 2013 Restricted shares
Stock-based compensation
Number of shares reserved for issuance			4,750,000		500,000
Vesting period								3 years	4 years
Expiration period						10 years
Number of shares available for grant	455,381			486,099
Number of Shares
Outstanding at the beginning of the period (in shares)						3,929,910
Outstanding at the end of the period (in shares)						3,929,910	3,929,910
Vested and exercisable at the end of the period (in shares)						2,651,513
Vested and exercisable at the end of the period and expected to vest thereafter (in shares)						3,929,910
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)						$ 9.03
Outstanding at the end of the period (in dollars per share)						$ 9.03	$ 9.03
Vested and exercisable at the end of the period (in dollars per share)						$ 11.37
Vested and exercisable at the end of the period and expected to vest thereafter (in dollars per share)						$ 9.03
Weighted-Average Remaining Contractual Term (in years)
Outstanding at the end of the period						7 years 6 months	7 years 9 months
Vested and exercisable at the end of the period						6 years 7 months 17 days
Vested and exercisable at the end of the period and expected to vest thereafter						7 years 6 months
Weighted-Average Grant-Date Fair Value
Outstanding (in dollars per share)						$ 3.84	$ 3.84
Vested and exercisable at the end of the period (in dollars per share)						$ 4.59
Vested and exercisable at the end of the period and expected to vest thereafter (in dollars per share)						$ 3.84
Aggregate Intrinsic Value
Outstanding at the beginning of the period						$ (26,959)
Outstanding at the end of the period						(26,959)	(26,959)
Vested and exercisable at the end of the period						(24,394)
Vested and exercisable at the end of the period and expected to vest thereafter						(26,959)
Stock-based compensation, additional disclosure
Closing stock price (in dollars per share)		$ 2.17
Number of units
Unvested at the beginning of the period (in shares)										128,060
Vested (in shares)										(4,626)
Unvested at the end of the period (in shares)										123,434
Expected to vest at the end of the period (in shares)										123,434
Weighted-Average Grant-Date Fair Value
Unvested at the beginning of the period (in dollars per share)										$ 7.46
Vested (in dollars per share)										$ 8.11
Unvested at the end of the period (in dollars per share)										$ 7.44
Expected to vest at the end of the period (in dollars per share)										$ 7.44
Unrecognized compensation cost
Unrecognized compensation cost						2,294				623
Weighted-average remaining vesting period of recognition						1 year				1 year 8 months 12 days
2010 ESPP
Discount rate (as a percent)				10.00%
Number of Offering periods				4
Stock-based compensation expense				$ 1
Shares available for purchase	455,381			486,099