EMPLOYEE STOCK PLANS - Stock Option Activity (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
Sep. 29, 2013
Number of Shares
Outstanding at December 31, 2012 (in shares)	7,614
Granted (in shares)	1,540
Exercised (in shares)	(291)
Canceled or forfeited (in shares)	(3,438)
Outstanding at June 30, 2013 (in shares)	5,425
Vested and expected to vest at June 30, 2013 (in shares)	4,954
Exercisable at June 30, 2013 (in shares)	2,107
Weighted-Average Exercise Price
Weighted-Average Exercise Price, Outstanding at December 31, 2012 (in usd per share)	$ 3.34
Weighted Average Exercise Price, Granted (in usd per share)	$ 1.36
Weighted Average Exercise Price, Exercised (in usd per share)	$ 0.84
Weighted Average Exercise Price, Canceled or forfeited (in usd per share)	$ 4.13
Weighted-Average Exercise Price, Outstanding at June 30, 2013 (in usd per share)	$ 2.41
Weighted Average Exercise Price, Vested and expected to vest at June 30, 2013 (in usd per share)	$ 2.50
Weighted Average Exercise Price, Exercisable at June 30, 2013 (in usd per share)	$ 4.01
Weighted Average Remaining Term
Weighted Average Remaining Term, Outstanding at June 30, 2013	4 years 9 months 19 days
Weighted Average Remaining Term, Vested and expected to vest at June 30, 2013	4 years 7 months 6 days
Weighted Average Remaining Term, Exercisable at June 30, 2013	2 years 9 months 18 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding at June 30, 2013	$ 4,104
Aggregate Intrinsic Value, Vested and expected to vest at June 30, 2013	3,668
Aggregate Intrinsic Value, Exercisable at June 30, 2013	$ 683

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Weighted average price of options that were either forfeited or expired.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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