Note 12 - Accumulated Other Comprehensive (Loss) Income - Summary of Activity in Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Balance, beginning				$ 158,876	$ 158,876	$ 153,859
Reclassifications from accumulated comprehensive loss to net income	[1]	$ 424	$ 452	1,714
Balance, ending					154,510	158,876
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance, beginning				(2,875)	(2,875)	(3,089)
Other comprehensive (loss) income before reclassifications					237	(176)
Reclassifications from accumulated comprehensive loss to net income					363	390
Net other comprehensive income					600	214
Reclassifications from accumulated comprehensive loss to accumulated deficit					(490)
Balance, ending					(2,765)	(2,875)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Interest Rate Swap [Member]
Balance, beginning				(35)	(35)	3
Other comprehensive (loss) income before reclassifications					278	(100)
Reclassifications from accumulated comprehensive loss to net income					61	62
Net other comprehensive income					339	(38)
Reclassifications from accumulated comprehensive loss to accumulated deficit					65
Balance, ending					369	(35)
AOCI Attributable to Parent [Member]
Balance, beginning				$ (2,910)	(2,910)	(3,086)
Other comprehensive (loss) income before reclassifications					515	(276)
Reclassifications from accumulated comprehensive loss to net income					424	452
Net other comprehensive income					939	176
Reclassifications from accumulated comprehensive loss to accumulated deficit					(425)
Balance, ending					$ (2,396)	$ (2,910)

[1] See Note 7 "Fair Value Measurements" for additional information regarding the Company's interest rate swaps.