Note 6 - Restructuring (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2021	Sep. 26, 2020	Oct. 02, 2021	Sep. 26, 2020
Restructuring Charges, Total	$ 166	$ 2,692	$ 546	$ 4,178
Q1 2020 Plan [Member]
Restructuring Charges, Total	0	600		2,000
Restructuring and Related Cost, Cost Incurred to Date	2,000		2,000
Q1 2020 Plan [Member] | Maximum [Member]
Restructuring Charges, Total			100
Q2 2019 Sales Plan [Member]
Restructuring Charges, Total	0		0
Restructuring and Related Cost, Cost Incurred to Date	2,100		2,100
Q2 2019 Sales Plan [Member] | Maximum [Member]
Restructuring Charges, Total		100		100
June 2017 Plan [Member]
Restructuring Charges, Total	100	$ 2,000	500	$ 2,100
Restructuring and Related Cost, Cost Incurred to Date	21,500		21,500
June 2017 Plan [Member] | Maximum [Member]
Restructuring and Related Cost, Expected Cost, Total	23,500		23,500
June 2017 Plan [Member] | Minimum [Member]
Restructuring and Related Cost, Expected Cost, Total	$ 21,500		$ 21,500