Note 7 - Accumulated Other Comprehensive Loss - Disclosure of Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017
Beginning Balance					$ 554,319
Ending Balance	$ 617,255				617,255
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Beginning Balance	(6,677)		$ (24,447)		(12,856)		$ (28,047)
Other comprehensive income (loss) before reclassifications	(10,658)		8,590		(4,479)		12,190
Amounts reclassified from AOCL
Other comprehensive loss	(10,658)		8,590		(4,479)		12,190
Ending Balance	(17,335)		(15,857)		(17,335)		(15,857)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Beginning Balance	(10,978)		(11,040)		(10,978)		(11,040)
Other comprehensive income (loss) before reclassifications
Amounts reclassified from AOCL
Other comprehensive loss
Ending Balance	(10,978)		(11,040)		(10,978)		(11,040)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Beginning Balance	9,283		(636)		2,636		(1,076)
Other comprehensive income (loss) before reclassifications	2,130	[1]	324	[2]	8,777	[3]	764	[4]
Amounts reclassified from AOCL
Other comprehensive loss	2,130		324		8,777		764
Ending Balance	11,413		(312)		11,413		(312)
AOCI Attributable to Parent [Member]
Beginning Balance	(8,372)		(36,123)		(21,198)		(40,163)
Other comprehensive income (loss) before reclassifications	(8,528)		8,914		4,298		12,954
Amounts reclassified from AOCL
Other comprehensive loss	(8,528)		8,914		4,298		12,954
Ending Balance	$ (16,900)		$ (27,209)		$ (16,900)		$ (27,209)

[1] Represents unrealized gains of $2,878, net of tax effect of $(748), for the three months ended June 30, 2018.

[2] Represents unrealized gains of $531, net of tax effect of $(207), for the three months ended June 30, 2017.

[3] Represents unrealized gains of $11,860, net of tax effect of $(3,083), for the six months ended June 30, 2018.

[4] Represents unrealized gains of $1,254, net of tax effect of $(490), for the six months ended June 30, 2017.