Note 8 - Pension - Components of Pension Expense (Details) - Defined Benefit Pension Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Service cost (benefits earned during the period)	$ 4,400	$ 5,151
Interest cost on projected benefit obligation	16,598	15,599
Expected return on plan assets	(20,781)	(22,658)
Prior service cost (credit)	(200)	(200)
Actuarial (gain) loss	4,809	7,094
Settlement charge	9	92
Pension expense	4,835	5,078
UNITED STATES
Service cost (benefits earned during the period)	3,368	4,009
Interest cost on projected benefit obligation	13,530	12,615
Expected return on plan assets	(20,781)	(22,658)
Prior service cost (credit)		1
Actuarial (gain) loss	4,396	6,472
Settlement charge	9
Pension expense	522	439
Foreign Plan [Member]
Service cost (benefits earned during the period)	1,032	1,142
Interest cost on projected benefit obligation	3,068	2,984
Expected return on plan assets
Prior service cost (credit)	(200)	(201)
Actuarial (gain) loss	413	622
Settlement charge		92
Pension expense	$ 4,313	$ 4,639