Note 3 - Accumulated Other Comprehensive Income (Details) - Amounts Reclassified out of Accumulated Other Comprehensive Income by Component (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	$ (1,405)	$ (1,120)
Net of tax	3,849	2,833
	5,479	4,490
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains and losses on available for sale investment securities	111	(78)
Income tax expense	(39)	27
Net of tax	72	(51)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	8	12
Net of tax	(15)	(23)
Prior service costs	(13)	(52)
Actuarial (losses) gains	(10)	17
	(23)	(35)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	$ 57	$ (74)