Note 11 - Accumulated Other Comprehensive Loss - Summary of Activity in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Balance, beginning	$ 169,750	$ 154,510
Reclassifications from accumulated comprehensive income (loss) to net income	(76)	47
Balance, ending	170,065	161,695
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance, beginning	(3,003)
Other comprehensive income before reclassifications	14
Reclassifications from accumulated comprehensive income (loss) to net income	87
Net other comprehensive income	101
Balance, ending	(2,902)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Interest Rate Swap [Member]
Balance, beginning	328
Other comprehensive income before reclassifications	(9)
Reclassifications from accumulated comprehensive income (loss) to net income	(163)
Net other comprehensive income	(172)
Balance, ending	156
AOCI Attributable to Parent [Member]
Balance, beginning	(2,675)	(2,396)
Other comprehensive income before reclassifications	5
Reclassifications from accumulated comprehensive income (loss) to net income	(76)
Net other comprehensive income	(71)
Balance, ending	$ (2,746)	$ (2,090)