Note 13 - Segment and Geographic Information - Net Sales by Geographical Area (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Oct. 01, 2016	Sep. 26, 2015	Oct. 01, 2016	Sep. 26, 2015
UNITED STATES
Net sales	[1]	$ 92,475	$ 85,049	$ 270,659	$ 258,030
CHINA
Net sales	[1]	70,215	49,345	181,134	143,694
Other Countries [Member]
Net sales	[1]	117,641	81,116	319,848	246,120
Net sales	[1]	$ 280,331	$ 215,510	$ 771,641	$ 647,844

[1] Sales by country represent sales to customer or distributor locations.