Note 2 - Significant Accounting Policies - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Balance	$ (1,852)
Other comprehensive income (loss) before reclassifications	78
Losses (gains) reclassified from accumulated other comprehensive income (loss)	(100)
Other comprehensive income (loss)	(22)	$ (585)	$ 299
Balance	(1,874)	(1,852)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance	(1,101)
Other comprehensive income (loss) before reclassifications	(158)
Losses (gains) reclassified from accumulated other comprehensive income (loss)	50
Other comprehensive income (loss)	(108)
Balance	(1,209)	(1,101)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Balance	9
Other comprehensive income (loss) before reclassifications	163
Losses (gains) reclassified from accumulated other comprehensive income (loss)	(172)
Other comprehensive income (loss)	(9)
Balance		9
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(455)
Other comprehensive income (loss) before reclassifications	24
Losses (gains) reclassified from accumulated other comprehensive income (loss)	22
Other comprehensive income (loss)	46
Balance	(409)	(455)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	(305)
Other comprehensive income (loss) before reclassifications	49
Losses (gains) reclassified from accumulated other comprehensive income (loss)
Other comprehensive income (loss)	49
Balance	$ (256)	$ (305)