Note 18 - Retirement Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 2,043	$ 2,214	$ 2,390
Expected return on plan assets	(3,169)	(2,707)	(2,649)
Recognized actuarial loss	719	798	776
Net periodic benefit cost	(407)	305	517
Pension Plan [Member] | International Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,009	941	742
Interest cost	720	732	740
Amortization of prior service cost/(benefit)	(5)	(5)	(5)
Recognized actuarial loss	384	361	194
Net periodic benefit cost	2,108	2,029	1,671
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		9	18
Amortization of prior service cost/(benefit)		57	57
Recognized actuarial loss	121	241	182
Net periodic benefit cost	$ 121	$ 307	$ 257