Stock-Based Compensation - Schedule of Stock Options Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jul. 01, 2018 USD ($) $ / shares shares
Number of Shares
Balance outstanding at beginning of period, (in shares) | shares	3,558
Forfeited or expired, (in shares) | shares	(50)
Balance outstanding at end of period, (in shares) | shares	3,508
Exercisable, (in shares) | shares	3,066
Vested and expected to vest, (in shares) | shares	3,430
Weighted Average Exercise Price
Balance outstanding at beginning of period, (in dollars per share) | $ / shares	$ 2.09
Forfeited or expired, (in dollars per share) | $ / shares	0
Balance outstanding at end of period, (in dollars per share) | $ / shares	2.08
Exercisable, (in dollars per share) | $ / shares	2.24
Vested and expected to vest, (in dollars per share) | $ / shares	$ 2.11
Weighted Average Remaining Term
Balance outstanding	3 years 10 months 20 days
Exercisable	3 years 3 months 14 days
Vested and expected to vest	3 years 9 months 18 days
Aggregate Intrinsic Value
Balance outstanding | $	$ 285
Exercisable | $	167
Vested and expected to vest | $	$ 263