Note 3 - Accumulated Other Comprehensive Income - Amounts Reclassified Out of Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income tax expense	$ (2,076)	$ (1,560)	$ (5,074)	$ (5,510)
Net income	5,312	4,324	13,123	14,060
Salaries and employee benefits	(7,309)	(7,810)	(22,572)	(23,444)
Total before tax	7,388	5,884	18,197	19,570
Reclassification out of Accumulated Other Comprehensive Income [Member]
Net income	1	2,445	(56)	2,566
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Unrealized gains (losses) on available for sale investment securities	3	3,776	(7)	3,990
Income tax expense	(1)	(1,322)	2	(1,397)
Net income	2	2,454	(5)	2,593
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Salaries and employee benefits		(12)	(75)	(37)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Salaries and employee benefits	(1)	(1)	(4)	(4)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Income tax expense		4	28	14
Net income	(1)	(9)	(51)	(27)
Total before tax	$ (1)	$ (13)	$ (79)	$ (41)