Note 3 - Accumulated Other Comprehensive Income (Details) - Amounts Reclassified out of Accumulated Other Comprehensive Income by Component - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	$ (1,369)	$ (1,959)	$ (2,774)	$ (3,079)
Net of tax	3,332	4,261	7,181	7,094
	4,871	6,783	10,350	11,273
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	16	(8)	71	(113)
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	48	23	155	(103)
Income tax expense	(17)	(8)	(54)	36
Net of tax	31	15	101	(67)
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	13	16	25
Net of tax	(15)	(23)	(30)	(46)
Prior service costs	(12)	(52)	(25)	(104)
Actuarial gains (losses)	(11)	16	(21)	33
	$ (23)	$ (36)	$ (46)	$ (71)