Note 3 - Accumulated Other Comprehensive Income (Details) - Amounts Reclassified out of Accumulated Other Comprehensive Income by Component - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	$ (1,439)	$ (1,283)	$ (4,213)	$ (4,362)
Net of tax	3,832	3,657	11,013	10,751
	5,271	5,390	15,621	16,663
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	(10)	(15)	41	(134)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains and losses on available for sale investment securities	8	11	132	(102)
Income tax expense	(3)	(4)	(46)	36
Net of tax	5	7	86	(66)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	8	12	24	37
Net of tax	(15)	(22)	(45)	(68)
Prior service costs	(13)	(51)	(38)	(155)
Actuarial (losses) gains	(10)	17	(31)	50
	$ (23)	$ (34)	$ (69)	$ (105)