Note 21 - Parent Company Only Financial Statements - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash and due from banks	$ 61,329	$ 76,254
Interest-bearing deposits at financial institutions	86,596	147,891
Securities available for sale, at fair value	361,966	210,695
Loans/leases receivable held for investment	4,247,371	3,686,532
Premises and equipment, net	72,693	73,859
Goodwill	74,066	74,748	$ 77,832	$ 28,334
Intangibles	11,381	14,970	17,450
Other assets	61,302	59,975
Total assets	5,682,797	4,909,050	4,949,710
Subordinated notes	118,691	68,394
Junior subordinated debentures	37,993	37,838
Other liabilities	83,483	90,253
Total liabilities	5,089,004	4,373,699
Common stock	15,806	15,828
Additional paid-in capital	275,807	274,785
Retained earnings	300,804	245,836
Total stockholders' equity	593,793	535,351	$ 473,138	$ 353,287
Total liabilities and stockholders' equity	5,682,797	4,909,050
Reportable Legal Entities [Member] | Parent Company [Member]
Cash and due from banks	88,610	59,529
Interest-bearing deposits at financial institutions	7,200	5,601
Premises and equipment, net	9,242	9,424
Goodwill		682
Intangibles		1,503
Other assets	7,225	15,150
Total assets	772,049	675,826
Subordinated notes	113,691	63,531
Junior subordinated debentures	37,993	37,838
Other liabilities	26,572	39,106
Total liabilities	178,256	140,475
Common stock	15,806	15,828
Additional paid-in capital	275,807	274,785
Retained earnings	300,804	245,836
Accumulated other comprehensive loss	1,376	(1,098)
Total stockholders' equity	593,793	535,351
Total liabilities and stockholders' equity	772,049	675,826
Reportable Legal Entities [Member] | Parent Company [Member] | Bank Subsidiaries [Member]
Investment in bank subsidiaries	655,232	570,698
Reportable Legal Entities [Member] | Parent Company [Member] | Non-bank Subsidiaries [Member]
Investment in bank subsidiaries	$ 4,540	$ 13,239