Note 7 - Leases (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2021	Sep. 26, 2020	Oct. 02, 2021	Sep. 26, 2020	Jan. 02, 2021
Operating Lease, Right-of-Use Asset	$ 24,822		$ 24,822		$ 22,178
Operating Lease, Weighted Average Remaining Lease Term (Year)	4 years 4 months 24 days		4 years 4 months 24 days
Operating Lease, Weighted Average Discount Rate, Percent	5.30%		5.30%
Operating Lease, Cost	$ 2,000	$ 1,900	$ 5,900	$ 5,700
Operating Lease Liability for Previously Restructured Facilities	7,400		7,400
Hillsboro, Oregon and Shanghai, China Facility Leases [Member]
Operating Lease, Right-of-Use Asset	$ 7,200		$ 7,200