Note 14 - Changes in Accumulated Other Comprehensive Income by Component (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Beginning balance, net of tax	$ 6,249,000	$ 7,724,000	$ (521,000)	$ 3,392,000
Other comprehensive income before reclassifications, net of tax	1,674,000	(5,477,000)	8,444,000	(1,145,000)
Amounts reclassified from accumulated other comprehensive income, net of tax		(36,000)		(36,000)
Total other comprehensive income (loss), net of tax	1,674,000	(5,513,000)	8,444,000	(1,181,000)
Ending balance, net of tax	7,923,000	2,211,000	7,923,000	2,211,000
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Beginning balance, net of tax	(4,938,000)	(6,131,000)	(5,041,000)	(6,299,000)
Other comprehensive income before reclassifications, net of tax
Amounts reclassified from accumulated other comprehensive income, net of tax	103,000	164,000	206,000	332,000
Total other comprehensive income (loss), net of tax	103,000	164,000	206,000	332,000
Ending balance, net of tax	(4,835,000)	(5,967,000)	(4,835,000)	(5,967,000)
Beginning balance, net of tax	1,311,000	1,593,000	(5,562,000)	(2,907,000)
Other comprehensive income before reclassifications, net of tax	1,674,000	(5,477,000)	8,444,000	(1,145,000)
Amounts reclassified from accumulated other comprehensive income, net of tax	103,000	128,000	206,000	296,000
Total other comprehensive income (loss), net of tax	1,777,000	(5,349,000)	8,650,000	(849,000)
Ending balance, net of tax	$ 3,088,000	$ (3,756,000)	$ 3,088,000	$ (3,756,000)