Note 12 - Other Comprehensive Income (Loss) - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income tax expense	$ 2,265	$ 3,555	$ 3,159	$ 3,052	$ 5,542	$ 4,096	$ 4,359	$ 3,142	$ 4,009	$ 3,883	$ 3,676	$ 3,676	$ 12,031	$ 17,139	$ 15,244
Reclassification out of Accumulated Other Comprehensive Income [Member]
Income tax expense													81
Reclassifications, net of income taxes													(151)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Realized loss on sale of available for sale securities													$ (232)