Note 7 - Leases - Lease Balance Classifications Within the Consolidated Balance Sheets and Lease Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Dec. 28, 2019
Balance	$ 23,591
Right-of-use assets obtained for new lease contracts during the period	2,274	$ 404
Reduction in the carrying amount of right-of-use assets during the period	(4,464)	(4,372)
Adjustments for present value and foreign currency effects	213
Balance	21,614
Balance	26,124
Lease liabilities incurred for new lease contracts during the period	2,274
Accretion of lease liabilities	1,247
Operating cash used by payments on lease liabilities	(5,786)	$ (6,540)
Adjustments for present value, foreign currency, and restructuring liability effects	208
Balance	24,067
Less: Current portion of operating lease liabilities	(4,562)		$ (4,686)
Long-term operating lease liabilities, net of current portion	$ 19,505		$ 21,438