Note 3 - Accumulated Other Comprehensive Income (Details) - Changes in Accumulated Other Comprehensive Income by Component - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 2,782	$ 4,875
Other comprehensive income (loss) before reclassifications	2,787	648
Amounts reclassified from accumulated other comprehensive income	(145)	(57)
Net current-period other comprehensive income (loss)	2,642	591
Ending balance	5,424	5,466
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	3,219	5,174
Other comprehensive income (loss) before reclassifications	2,787	1,899
Amounts reclassified from accumulated other comprehensive income	(154)	(72)
Net current-period other comprehensive income (loss)	2,633	1,827
Ending balance	5,852	7,001
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(437)	(299)
Other comprehensive income (loss) before reclassifications	0	(1,251)
Amounts reclassified from accumulated other comprehensive income	9	15
Net current-period other comprehensive income (loss)	9	(1,236)
Ending balance	$ (428)	$ (1,535)