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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Federal and State Income Taxes
Computed "expected" tax expense									$ 15,126	$ 10,948	$ 14,229
Tax exempt income, net									(4,470)	(3,958)	(5,654)
Bank-owned life insurance									(360)	(343)	(631)
State income taxes, net of federal benefit, current year									3,668	2,681	1,765
Change in unrecognized tax benefits									(93)	(45)	(54)
Goodwill impairment									630
Intended liquidation of bank-owned life insurance									790
Tax credits									705	154	341
Acquisition costs										227
Excess tax benefit on stock options exercised and restricted stock awards vested									(287)	(425)	(1,220)
Re-measurement of deferred tax asset to incorporate newly enacted tax rates											(2,919)
Other									320	84	(229)
Federal and state income tax expense	$ 6,560	$ 3,573	$ 3,073	$ 1,413	$ 3,535	$ 1,608	$ 1,881	$ 1,991	$ 14,619	$ 9,015	$ 4,946
Computed "expected" tax expense (in percentage)									21.00%	21.00%	35.00%
Tax exempt income, net (in percentage)									(6.20%)	(7.60%)	(13.90%)
Bank-owned life insurance (in percentage)									(0.50%)	(0.60%)	(1.50%)
State income taxes, net of federal benefit, current year (in percentage)									5.10%	5.20%	4.30%
Change in unrecognized tax benefits (in percentage)									(0.10%)	(0.10%)	(0.10%)
Goodwill impairment (in percentage)									0.90%
Intended liquidation of bank-owned life insurance (in percentage)									1.10%
Tax credits (in percentage)									(1.00%)	(0.30%)	(0.80%)
Acquisition costs (in percentage)										0.40%
Excess tax benefit on stock options exercised and restricted stock awards vested (in percentage)									(0.40%)	(0.80%)	(3.00%)
Re-measurement of deferred tax asset to incorporate newly enacted tax rates (in percentage)											(7.20%)
Other (in percentage)									0.40%	0.10%	(0.60%)
Federal and state income tax expense (in percentage)									20.30%	17.30%	12.20%