Segment, Geographic, Product and Significant Customer Information - Net Revenue (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 28, 2015 segment	Mar. 29, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments	1
Total net revenues:
Total net revenues	$ 50,376	$ 51,576
United States [Member]
Total net revenues:
Total net revenues	9,078	6,741
South Korea [Member]
Total net revenues:
Total net revenues	14,643	15,889
China [Member]
Total net revenues:
Total net revenues	4,001	15,488
Taiwan [Member]
Total net revenues:
Total net revenues	14,428	4,416
Other [Member]
Total net revenues:
Total net revenues	$ 8,226	$ 9,042