Note 4 - Loans Leases Receivable - Allowance for Estimated Losses on Loans Leases (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Balance	$ 37,545,076	$ 33,356,632	$ 34,355,728	$ 30,757,448
Provision for loan/lease losses	6,205,828	2,086,436	11,046,402	6,214,538
Loans/leases charged off	(990,648)	(649,724)	(2,951,381)	(2,393,953)
Recoveries on loans/leases previously charged off	317,201	188,997	626,708	404,308
Balance	43,077,457	34,982,341	43,077,457	34,982,341
Allowance for impaired loans/leases					$ 9,035,501	$ 3,043,319
Allowance for nonimpaired loans/leases					34,041,956	31,312,409
Less allowance for estimated losses on loans/leases	37,545,076	33,356,632	34,355,728	30,757,448	43,077,457	34,355,728
Impaired loans/leases					30,545,602	18,354,163
Nonimpaired loans/leases					3,613,553,901	2,938,359,330
Loans and Leases Receivable, Net of Deferred Income					$ 3,644,099,503	$ 2,956,713,493
Allowance as a percentage of impaired loans/leases					29.58%	16.58%
Allowance as a percentage of nonimpaired loans/leases					0.94%	1.07%
Total allowance as a percentage of total loans/leases					1.18%	1.16%
Commercial Portfolio Segment [Member]
Balance	15,233,871	14,207,733	14,323,036	12,545,110
Provision for loan/lease losses	3,698,588	469,977	5,283,763	2,345,121
Loans/leases charged off	(87,040)	(338,361)	(911,429)	(630,704)
Recoveries on loans/leases previously charged off	71,440	63,366	221,489	143,188
Balance	18,916,859	14,402,715	18,916,859	14,402,715
Allowance for impaired loans/leases					$ 4,787,321	$ 715,627
Allowance for nonimpaired loans/leases					14,129,538	13,607,409
Less allowance for estimated losses on loans/leases	15,233,871	14,207,733	14,323,036	12,545,110	18,916,859	14,323,036
Impaired loans/leases					11,064,848	6,248,209
Nonimpaired loans/leases					1,369,477,676	1,128,268,106
Loans and Leases Receivable, Net of Deferred Income					$ 1,380,542,524	$ 1,134,516,315
Allowance as a percentage of impaired loans/leases					43.27%	11.45%
Allowance as a percentage of nonimpaired loans/leases					1.03%	1.21%
Total allowance as a percentage of total loans/leases					1.37%	1.26%
Commercial Real Estate Portfolio Segment [Member]
Balance	15,819,040	12,999,233	13,962,688	11,670,609
Provision for loan/lease losses	2,254,313	1,349,393	4,091,170	2,655,521
Loans/leases charged off	(387,499)		(387,499)	(10,375)
Recoveries on loans/leases previously charged off	30,344	10,748	49,839	43,619
Balance	17,716,198	14,359,374	17,716,198	14,359,374
Allowance for impaired loans/leases					$ 3,555,829	$ 1,429,460
Allowance for nonimpaired loans/leases					14,160,369	12,533,228
Less allowance for estimated losses on loans/leases	15,819,040	12,999,233	13,962,688	11,670,609	17,716,198	13,962,688
Impaired loans/leases					15,944,006	6,529,262
Nonimpaired loans/leases					1,711,382,184	1,296,962,620
Loans and Leases Receivable, Net of Deferred Income					$ 1,727,326,190	$ 1,303,491,882
Allowance as a percentage of impaired loans/leases					22.30%	21.89%
Allowance as a percentage of nonimpaired loans/leases					0.83%	0.97%
Total allowance as a percentage of total loans/leases					1.03%	1.07%
Finance Leases Portfolio Segment [Member]
Balance	2,724,355	2,638,301	2,382,098	3,111,898
Provision for loan/lease losses	124,803	179,190	1,417,494	981,877
Loans/leases charged off	(427,638)	(268,669)	(1,505,824)	(1,611,432)
Recoveries on loans/leases previously charged off	210,727	103,936	338,479	170,415
Balance	2,632,247	2,652,758	2,632,247	2,652,758
Allowance for impaired loans/leases					$ 363,439	$ 504,469
Allowance for nonimpaired loans/leases					2,268,808	1,877,629
Less allowance for estimated losses on loans/leases	2,724,355	2,638,301	2,382,098	3,111,898	2,632,247	2,382,098
Impaired loans/leases					2,147,125	3,669,492
Nonimpaired loans/leases					124,604,658	137,778,740
Loans and Leases Receivable, Net of Deferred Income					$ 126,751,783	$ 141,448,232
Allowance as a percentage of impaired loans/leases					16.93%	13.75%
Allowance as a percentage of nonimpaired loans/leases					1.82%	1.36%
Total allowance as a percentage of total loans/leases					2.08%	1.68%
Residential Portfolio Segment [Member]
Balance	2,433,102	2,430,454	2,466,431	2,342,344
Provision for loan/lease losses	131,977	(11,654)	149,923	148,017
Loans/leases charged off	(58,241)	(25,822)	(110,566)	(101,006)
Recoveries on loans/leases previously charged off		6,000	1,050	9,623
Balance	2,506,838	2,398,978	2,506,838	2,398,978
Allowance for impaired loans/leases					$ 226,263	$ 355,167
Allowance for nonimpaired loans/leases					2,280,575	2,111,264
Less allowance for estimated losses on loans/leases	2,433,102	2,430,454	2,466,431	2,342,344	2,506,838	2,466,431
Impaired loans/leases					1,148,009	1,704,846
Nonimpaired loans/leases					308,139,526	256,941,419
Loans and Leases Receivable, Net of Deferred Income					$ 309,287,535	$ 258,646,265
Allowance as a percentage of impaired loans/leases					19.71%	20.83%
Allowance as a percentage of nonimpaired loans/leases					0.74%	0.82%
Total allowance as a percentage of total loans/leases					0.81%	0.95%
Consumer Portfolio Segment [Member]
Balance	1,334,708	1,080,911	1,221,475	1,087,487
Provision for loan/lease losses	(3,853)	99,530	104,052	84,002
Loans/leases charged off	(30,230)	(16,872)	(36,063)	(40,436)
Recoveries on loans/leases previously charged off	4,690	4,947	15,851	37,463
Balance	1,305,315	1,168,516	1,305,315	1,168,516
Allowance for impaired loans/leases					$ 102,649	$ 38,596
Allowance for nonimpaired loans/leases					1,202,666	1,182,879
Less allowance for estimated losses on loans/leases	$ 1,334,708	$ 1,080,911	$ 1,221,475	$ 1,087,487	1,305,315	1,221,475
Impaired loans/leases					241,614	202,354
Nonimpaired loans/leases					99,949,857	118,408,445
Loans and Leases Receivable, Net of Deferred Income					$ 100,191,471	$ 118,610,799
Allowance as a percentage of impaired loans/leases					42.48%	19.07%
Allowance as a percentage of nonimpaired loans/leases					1.20%	1.00%
Total allowance as a percentage of total loans/leases					1.30%	1.03%