Note 9 - Employee Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Apr. 01, 2018
Nora Defined Benefit Plan [Member]
Service cost	$ 217
Interest cost	174
Net periodic benefit cost	391
Service cost	217
Interest cost	174
Foreign Plan [Member]
Service cost	185	$ 187
Interest cost	1,281	1,353
Expected return on assets	(1,445)	(1,602)
Amortization of prior service cost	16	7
Amortization of net actuarial (gains)/losses	253	288
Net periodic benefit cost	290	233
Amortization of prior service cost	16	7
Amortization of net actuarial (gains)/losses	253	288
Service cost	185	187
Interest cost	1,281	1,353
UNITED STATES | Salary Continuation Plan [Member]
Service cost	0	0
Interest cost	288	270
Amortization of prior service cost	0	0
Amortization of net actuarial (gains)/losses	94	116
Net periodic benefit cost	382	386
Amortization of prior service cost	0	0
Amortization of net actuarial (gains)/losses	94	116
Service cost	0	0
Interest cost	$ 288	$ 270