Note 16 - Accumulated Other Comprehensive Loss - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ 544,864	$ 405,427
Balance	653,727	544,864
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(12,040)	(34,290)
Other comprehensive loss before reclassifications	(15,696)	22,250
Net current-period other comprehensive loss	(15,696)	22,250
Balance	(27,736)	(12,040)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(30,188)	(31,230)
Other comprehensive loss before reclassifications	(3,155)	121
Amounts reclassified from accumulated other comprehensive loss	942	921
Net current-period other comprehensive loss	(2,213)	1,042
Balance	(32,401)	(30,188)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(42,228)	(65,520)
Other comprehensive loss before reclassifications	(18,851)	22,371
Amounts reclassified from accumulated other comprehensive loss	942	921
Net current-period other comprehensive loss	(17,909)	23,292
Balance	$ (60,137)	$ (42,228)