Note 2 - Comprehensive Income (Details) - Components of Accumulated Other Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income, net of tax, beginning of period			$ 10,785
Current period change	$ 3,025	$ 60	(974)	$ 10,588
Accumulated other comprehensive income, net of tax, end of period	9,811		9,811
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income, net of tax, beginning of period			13,460
Current period change			(1,011)
Accumulated other comprehensive income, net of tax, end of period	12,449		12,449
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income, net of tax, beginning of period			(2,675)
Current period change			37
Accumulated other comprehensive income, net of tax, end of period	$ (2,638)		$ (2,638)