Supplementary Financial Information (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 29, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jul. 01, 2012	Apr. 01, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Net revenues	$ 40,783	$ 33,840	$ 24,574	$ 20,237	$ 20,740	$ 20,398	$ 34,884	$ 50,504	$ 119,434	$ 126,526	$ 184,947
Gross margin	13,147	11,424	8,467	4,368	6,977	7,734	13,255	16,934	37,406	44,900	56,248
Income (loss) from operations	2,029	(230)	(3,059)	(9,753)	(8,788)	(6,141)	(3,072)	(1,283)	(11,013)	(19,284)	(16,550)
Net income (loss)	$ 2,512	$ (412)	$ (3,567)	$ (9,508)	$ (8,820)	$ (6,034)	$ (3,346)	$ (1,119)	$ (10,975)	$ (19,319)	$ (17,950)
Net income (loss) per share:
Basic	$ 0.04	$ (0.01)	$ (0.06)	$ (0.16)
Diluted	$ 0.04	$ (0.01)	$ (0.06)	$ (0.16)
Basic and diluted (in usd per share)					$ (0.15)	$ (0.10)	$ (0.06)	$ (0.02)	$ (0.19)	$ (0.33)	$ (0.32)
Shares used in computing net income (loss) per share:
Weighted-average shares outstanding - basic	59,127	59,024	58,891	58,728					58,944	58,538	55,299
Diluted	60,830	59,024	58,891	58,728					58,944	58,538	55,299
Basic and Diluted (in shares)					58,638	58,586	58,507	58,420	58,944	58,538	55,299