Note 14 - Federal and State Income Taxes - Reconciliation of the Expected Federal Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Federal and State Income Taxes
Computed "expected" tax expense									$ 15,391	$ 15,126	$ 10,948
Tax exempt income, net									(5,943)	(4,470)	(3,958)
Bank-owned life insurance									(308)	(360)	(343)
State income taxes, net of federal benefit, current year									3,622	3,668	2,681
Change in unrecognized tax benefits									546	(93)	(45)
Goodwill impairment									105	630
Intended liquidation of bank-owned life insurance										790
Tax Credits									(456)	(705)	(154)
Acquisition costs											227
Excess tax benefit on stock options exercised and restricted stock awards vested									(242)	(287)	(425)
Other									(215)	320	84
Federal and state income tax expense	$ 4,009	$ 4,016	$ 2,798	$ 1,884	$ 6,560	$ 3,573	$ 3,073	$ 1,413	$ 12,707	$ 14,619	$ 9,015
Computed "expected" tax expense (in percentage)									21.00%	21.00%	21.00%
Tax exempt income, net (in percentage)									(8.10%)	(6.20%)	(7.60%)
Bank-owned life insurance (in percentage)									(0.40%)	(0.50%)	(0.60%)
State income taxes, net of federal benefit, current year (in percentage)									4.90%	5.10%	5.20%
Change in unrecognized tax benefits (in percentage)									0.70%	(0.10%)	(0.10%)
Goodwill impairment (in percentage)									0.10%	0.90%
Intended liquidation of bank-owned life insurance (in percentage)										1.10%
Tax credits (in percentage)									(0.60%)	(1.00%)	(0.30%)
Acquisition costs (in percentage)											0.40%
Excess tax benefit on stock options exercised and restricted stock awards vested (in percentage)									(0.30%)	(0.40%)	(0.80%)
Other (in percentage)									(0.30%)	0.40%	0.10%
Federal and state income tax expense (in percentage)									17.30%	20.30%	17.30%