Note 20 - Parent Company Only Financial Statements - Condensed Statements of Cash Flows (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income (loss)	$ 13,315,518	$ 8,808,835	$ 10,445,385	$ 10,549,961	$ 9,901,590	$ 7,853,935	$ 8,766,017	$ 9,184,965	$ 43,119,699	$ 35,706,507	$ 27,686,787
Depreciation									4,450,758	3,948,934	3,424,140
Stock-based compensation expense									1,443,346	1,187,036	947,174
Securities gains, net										87,885	(4,592,398)
Losses on debt extinguishment, net											4,577,668
Net decrease (increase) in interest-bearing deposits at financial institutions									(14,508,687)	12,137,820	(12,904,803)
Calls, maturities and redemptions									23,931,014	43,010,478	117,876,284
Sales									1,938,043	71,091,580	134,188,737
Purchase of premises and equipment									(11,457,086)	(5,760,802)	(6,032,416)
Net cash (used in) provided by investing activities									(333,648,270)	(410,516,757)	(168,975,229)
Proceeds from other borrowings									9,000,000	7,000,000	35,000,000
Calls, maturities and scheduled principal payments									(12,550,000)	(21,000,000)
Prepayments											(69,769,000)
Retirement of junior subordinated debentures											(3,955,000)
Net cash provided by financing activities									279,178,544	381,955,146	154,420,080
Net decrease in cash and due from banks									9,801,022	5,151,670	28,827,672
Cash and due from banks, beginning				75,721,663				70,569,993	75,721,663	70,569,993	41,742,321
Cash and due from banks, ending	85,522,685				75,721,663				85,522,685	75,721,663	70,569,993
Common Stock Offering 2 [Member]
Proceeds from issuance of common stock, net									1,279,153	2,055,507	31,934,690
Parent Company [Member]
Net income (loss)									43,119,699	35,706,507	27,686,787
Accretion of acquisition fair value adjustments									183,556	149,010	136,150
Depreciation									248,827	225,947	222,256
Stock-based compensation expense									1,443,346	1,187,036	947,174
Securities gains, net										(6,312)	(37,596)
Losses on debt extinguishment, net											(1,200,000)
Decrease (increase) in other assets									2,232,402	(968,808)	(2,346,253)
(Decrease) increase in other liabilities									(7,226,127)	(6,918,921)	5,105,251
Net cash provided by operating activities									19,791,532	5,234,256	23,046,243
Net decrease (increase) in interest-bearing deposits at financial institutions									(999,951)	50	50
Purchases											(3,873,060)
Calls, maturities and redemptions										(6,312)	(3,800,000)
Sales										31,713	132,738
Capital infusion, bank subsidiaries									(3,500,000)
Net cash paid for acquisitions									(5,182,804)	(3,368,909)	(80,000,000)
Purchase of premises and equipment									(2,257,295)	(68,842)	(824,498)
Net cash (used in) provided by investing activities									11,940,050	3,399,676	80,764,770
Proceeds from other borrowings									9,000,000	7,000,000	35,000,000
Calls, maturities and scheduled principal payments									(12,550,000)	(11,000,000)
Retirement of junior subordinated debentures											(3,955,000)
Payment of cash dividends on common and preferred stock									(3,300,091)	(2,494,260)	(1,981,541)
Net cash provided by financing activities									(5,570,938)	(4,438,753)	60,998,149
Net increase (decrease) in cash and due from banks									2,280,544	(2,604,173)	3,279,622
Cash and due from banks, beginning				$ 4,325,582				$ 6,929,755	4,325,582	6,929,755	3,650,133
Cash and due from banks, ending	$ 6,606,126				$ 4,325,582				6,606,126	4,325,582	6,929,755
Parent Company [Member] | Common Stock Offering 2 [Member]
Proceeds from issuance of common stock, net									1,279,153	2,055,507	31,934,690
Parent Company [Member] | Bank Subsidiaries [Member]
Earnings of bank subsidiaries									(55,209,382)	(45,103,593)	(33,467,712)
Distributions from bank subsidiaries									34,500,000	21,000,000	26,000,000
Parent Company [Member] | Non-bank Subsidiaries [Member]
Earnings of bank subsidiaries									435,941	(75,344)	(32,674)
Distributions from bank subsidiaries									$ 63,270	$ 38,734	$ 32,860