Note 18 - Retirement Plans - Benefit Obligations (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]
Benefit obligation, beginning of year	$ 59,186	$ 57,718
Interest cost	2,043	2,214	$ 2,390
Actuarial (gain)/loss	(4,218)	2,676
Benefits paid	(3,590)	(3,422)
Benefit obligation, end of year	53,421	59,186	57,718
Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation, beginning of year	29,423	25,002
Service cost	1,009	941	742
Interest cost	720	732	740
Actuarial (gain)/loss	2,295	798
Benefits paid	(730)	(725)
Currency translation effect	(2,551)	2,675
Benefit obligation, end of year	30,166	29,423	25,002
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation, beginning of year	609	1,209
Interest cost		9	18
Benefits paid	$ (609)	(609)
Benefit obligation, end of year		$ 609	$ 1,209