Note 2 - Business Acquisitions - Preliminary Allocation of Intangible Assets (Details) - Kita Manufacturing Co. LTD. and Kita USA, Inc. [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2018	Dec. 30, 2017
Gross carrying amount	$ 34,907	$ 35,212
Accumulated amortization	21,395	18,464
Developed Technology Rights [Member]
Gross carrying amount	20,632	20,780
Accumulated amortization	$ 14,468	12,623
Finite-lived intangible assets, average useful life (Year)	2 years 255 days
Customer Relationships [Member]
Gross carrying amount	$ 7,877	7,934
Accumulated amortization	$ 5,572	4,838
Finite-lived intangible assets, average useful life (Year)	2 years 109 days
Trade Names [Member]
Gross carrying amount	$ 6,088	6,185
Accumulated amortization	$ 1,301	972
Finite-lived intangible assets, average useful life (Year)	11 years 182 days
Noncompete Agreements [Member]
Gross carrying amount	$ 310	313
Accumulated amortization	$ 54	$ 31
Finite-lived intangible assets, average useful life (Year)	8 years 109 days