Note 20 - Parent Company Only Financial Statements - Condensed Balance Sheets (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash and due from banks	$ 85,522,685	$ 75,721,663
Interest-bearing deposits at financial institutions	133,198,095	55,765,012
Securities available for sale, at fair value	261,056,448	272,907,907
Loans/leases receivable, held for investment	3,731,458,642	2,963,840,399
Premises and equipment, net	75,582,118	62,838,255
Goodwill	77,831,902	28,334,092	$ 13,110,913	$ 3,222,688
Other assets	75,001,310	45,817,687
Total assets	4,949,710,195	3,982,664,773	3,301,943,748
Other borrowings	72,032,318	66,000,000
Other liabilities	94,572,661	53,242,979
Total liabilities	4,476,571,792	3,629,377,644
Common stock	15,718,208	13,918,168
Additional paid-in capital	270,760,511	189,077,550
Retained earnings	192,203,333	151,962,661
Total stockholders' equity	473,138,403	353,287,129	$ 286,040,799	$ 225,885,750
Total liabilities and stockholders' equity	4,949,710,195	3,982,664,773
Parent Company [Member]
Cash and due from banks	6,606,126	4,325,582
Interest-bearing deposits at financial institutions	1,000,552	601
Securities available for sale, at fair value		1,690,726
Loans/leases receivable, held for investment		1,710,000
Premises and equipment, net	6,956,040	4,947,572
Goodwill	3,766,074
Intangibles	1,854,932
Other assets	14,794,944	11,630,304
Total assets	572,022,176	437,366,647
Other borrowings	32,250,000	31,000,000
Junior subordinated debentures	37,670,043	37,486,487
Other liabilities	28,963,730	15,593,031
Total liabilities	98,883,773	84,079,518
Common stock	15,718,208	13,918,168
Additional paid-in capital	270,760,511	189,077,550
Retained earnings	192,203,333	151,962,661
Accumulated other comprehensive loss	(5,543,649)	(1,671,250)
Total stockholders' equity	473,138,403	353,287,129
Total liabilities and stockholders' equity	572,022,176	437,366,647
Parent Company [Member] | Bank Subsidiaries [Member]
Investment in bank subsidiaries	532,163,635	410,105,525
Parent Company [Member] | Non-bank Subsidiaries [Member]
Investment in bank subsidiaries	$ 4,879,873	$ 2,956,337