Segment, Geographic, Product and Significant Customer Information - Revenue Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Net revenues:
Total net revenues	$ 56,675	$ 58,714	$ 180,416	$ 161,970
South Korea [Member]
Net revenues:
Total net revenues	22,269	15,710	72,388	35,226
Japan [Member]
Net revenues:
Total net revenues	4,781	11,765	17,400	24,669
United States [Member]
Net revenues:
Total net revenues	6,231	8,211	28,101	24,306
China [Member]
Net revenues:
Total net revenues	3,403	7,364	17,420	33,883
Taiwan [Member]
Net revenues:
Total net revenues	2,304	6,334	19,016	16,962
Singapore [Member]
Net revenues:
Total net revenues	9,774	5,078	12,229	18,645
Other [Member]
Net revenues:
Total net revenues	$ 7,913	$ 4,252	$ 13,862	$ 8,279