Note 21 - Parent Company Only Financial Statements - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and due from banks	$ 76,254	$ 85,523
Interest-bearing deposits at financial institutions	147,891	133,198
Securities available for sale, at fair value	210,695	261,056
Loans/leases receivable, held for investment	3,686,532	3,731,459
Premises and equipment, net	73,859	75,582
Goodwill	74,748	77,832	$ 28,334	$ 13,111
Intangibles	14,970	17,450	9,079
Other assets	147,802	75,001
Total assets	4,909,050	4,949,710	3,982,665
Other borrowings		67,250
Subordinated notes	68,394	4,782
Junior subordinated debentures	37,838	37,670
Other liabilities	178,690	94,573
Total liabilities	4,373,699	4,476,572
Common stock	15,828	15,718
Additional paid-in capital	274,785	270,761
Retained earnings	245,836	192,203
Total stockholders' equity	535,351	473,138	$ 353,287	$ 286,041
Total liabilities and stockholders' equity	4,909,050	4,949,710
Reportable Legal Entities [Member] | Parent Company [Member]
Cash and due from banks	59,529	6,606
Interest-bearing deposits at financial institutions	5,601	1,001
Premises and equipment, net	9,424	6,956
Goodwill	682	3,766
Intangibles	1,503	1,855
Other assets	15,150	14,794
Total assets	675,826	572,022
Other borrowings		32,250
Subordinated notes	63,531
Junior subordinated debentures	37,838	37,670
Other liabilities	39,106	28,964
Total liabilities	140,475	98,884
Common stock	15,828	15,718
Additional paid-in capital	274,785	270,761
Retained earnings	245,836	192,203
Accumulated other comprehensive loss	(1,098)	(5,544)
Total stockholders' equity	535,351	473,138
Total liabilities and stockholders' equity	675,826	572,022
Reportable Legal Entities [Member] | Parent Company [Member] | Bank Subsidiaries [Member]
Investment in bank subsidiaries	570,698	532,164
Reportable Legal Entities [Member] | Parent Company [Member] | Non-bank Subsidiaries [Member]
Investment in bank subsidiaries	$ 13,239	$ 4,880