Note 3 - Accumulated Other Comprehensive (Loss) Income - Amounts Reclassified Out of Accumulated Other Comprehensive (Loss) Income by Component (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income tax expense	$ (1,160)	$ (1,276)
Net income	5,641	3,329
Salaries and employee benefits	(7,490)	(7,860)
Total before tax	6,801	4,605
Reclassification out of Accumulated Other Comprehensive Income [Member]
Net income	1	(55)
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		(9)
Income tax expense		3
Net income		(6)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Salaries and employee benefits		(75)
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)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Income tax expense		27
Net income	1	(49)
Total before tax	$ 1	$ (76)