Note 12 - Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2019	Mar. 31, 2018
Balance		$ 180,276	$ 163,297	$ 176,470	$ 157,960
Net current period other comprehensive (loss) income		(2,524)	(1,117)	(2,743)	(4,408)
Effect of adoption of ASU							$ 3,497
Balance		170,640	173,311	170,640	173,311
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance				(22,635)
Other comprehensive (loss) income before reclassifications				(2,854)
Amount reclassified from accumulated other comprehensive loss
Net current period other comprehensive (loss) income				(2,854)
Balance		(25,489)		(25,489)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member] | Accounting Standards Update 2018-02 [Member]
Effect of adoption of ASU
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Balance				12
Other comprehensive (loss) income before reclassifications
Amount reclassified from accumulated other comprehensive loss
Net current period other comprehensive (loss) income
Balance		12		12
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] | Accounting Standards Update 2018-02 [Member]
Effect of adoption of ASU
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance				(2,215)
Other comprehensive (loss) income before reclassifications				16
Amount reclassified from accumulated other comprehensive loss	[1]			94
Net current period other comprehensive (loss) income				110
Balance		(2,568)		(2,568)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] | Accounting Standards Update 2018-02 [Member]
Effect of adoption of ASU		(463)		(463)
AOCI Attributable to Parent [Member]
Balance		(25,521)	(22,916)	(24,838)	(19,625)
Other comprehensive (loss) income before reclassifications				(2,838)
Amount reclassified from accumulated other comprehensive loss				94
Net current period other comprehensive (loss) income				(2,744)
Effect of adoption of ASU						$ (463)
Balance		(28,045)	$ (24,033)	(28,045)	$ (24,033)
AOCI Attributable to Parent [Member] | Accounting Standards Update 2018-02 [Member]
Effect of adoption of ASU		$ (463)		$ (463)

[1] This reclassification relates to the amortization of prior service costs and gains/losses associated with the Company's SERP Plan. This expense is allocated between cost of sales and selling, general and administrative expense based upon the employment classification of the plan participants.