Note 6 - Restructuring - Activity Related to Restructuring Plans (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Oct. 02, 2021	Sep. 26, 2020	Oct. 02, 2021	Sep. 26, 2020
Restructuring charges		$ 166	$ 2,692	$ 546	$ 4,178
Employee Severance [Member]
Accrued Restructuring	[1]			246	160
Restructuring charges	[1]			15	1,733
Costs paid or otherwise settled	[1]			(165)	(1,254)
Accrued Restructuring	[1]	96	639	96	639
Lease Termination and Fixed Assets [Member]
Accrued Restructuring				8,233	6,585
Restructuring charges				531	2,132
Costs paid or otherwise settled				(1,346)	(1,275)
Accrued Restructuring		7,418	7,442	7,418	7,442
Software Contracts and Engineering Tools [Member]
Accrued Restructuring	[2]			664	865
Restructuring charges	[2]			0	313
Costs paid or otherwise settled	[2]			(664)	(526)
Accrued Restructuring	[2]	0	652	0	652
Other Restructuring [Member]
Accrued Restructuring				9,143	7,610
Restructuring charges				546	4,178
Costs paid or otherwise settled				(2,175)	(3,055)
Accrued Restructuring		$ 7,514	$ 8,733	$ 7,514	$ 8,733

[1] Includes employee relocation and outplacement costs.

[2] Includes termination fees on the cancellation of certain contracts under the Q2 2019 Sales Plan