Note 10 - Accumulated Other Comprehensive Loss - AOCI Change (Details) - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Balance, Beginning of Period	$ 297,855
Balance, End of Period	324,332
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance, Beginning of Period	(19,233)	$ (10,639)
Other comprehensive income (loss) before reclassifications	10,677	(2,388)
Net loss reclassified from accumulated other comprehensive loss
Other Comprehensive Income (Loss)	10,677	(2,388)
Balance, End of Period	(8,556)	(13,027)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance, Beginning of Period	(219)	(82)
Other comprehensive income (loss) before reclassifications	(138)	132
Net loss reclassified from accumulated other comprehensive loss		(31)
Other Comprehensive Income (Loss)	(138)	101
Balance, End of Period	(357)	19
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance, Beginning of Period	(9,093)	(9,545)
Other comprehensive income (loss) before reclassifications
Net loss reclassified from accumulated other comprehensive loss
Other Comprehensive Income (Loss)
Balance, End of Period	(9,093)	(9,545)
AOCI Attributable to Parent [Member]
Balance, Beginning of Period	(28,545)	(20,266)
Other comprehensive income (loss) before reclassifications	10,539	(2,256)
Net loss reclassified from accumulated other comprehensive loss		(31)
Other Comprehensive Income (Loss)	10,539	(2,287)
Balance, End of Period	$ (18,006)	$ (22,553)