Note 12 - Accumulated Other Comprehensive (Loss)/Income - Schedule of Changes in Accumulated Other Comprehensive (Loss)/Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ 659,327	$ 592,737	$ 653,727	$ 544,864
Balance	676,585	623,327	676,585	623,327
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(32,514)	(9,111)	(27,736)	(12,040)
Other comprehensive income/(loss) before reclassifications	2,432	(13,465)	(2,346)	(10,536)
Net current-period other comprehensive income/(loss)	2,432	(13,465)	(2,346)	(10,536)
Balance	(30,082)	(22,576)	(30,082)	(22,576)
Interest Rate Swap [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(1,996)
Other comprehensive income/(loss) before reclassifications	(2,729)		(4,731)
Amounts reclassified from accumulated other comprehensive loss	30		36
Net current-period other comprehensive income/(loss)	(2,699)		(4,695)
Balance	(4,695)		(4,695)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(32,160)	(29,893)	(32,401)	(30,188)
Amounts reclassified from accumulated other comprehensive loss	239	206	480	501
Net current-period other comprehensive income/(loss)	239	206	480	501
Balance	(31,921)	(29,687)	(31,921)	(29,687)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(66,670)	(39,004)	(60,137)	(42,228)
Other comprehensive income/(loss) before reclassifications	(297)	(13,465)	(7,077)	(10,536)
Amounts reclassified from accumulated other comprehensive loss	269	206	516	501
Net current-period other comprehensive income/(loss)	(28)	(13,259)	(6,561)	(10,035)
Balance	$ (66,698)	$ (52,263)	$ (66,698)	$ (52,263)