Note 3 - Loans Leases Receivable - Allowance for Estimated Losses on Loans Leases (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
Balance	$ 36,532,602	$ 32,059,150	$ 34,355,728	$ 30,757,448
Provision for loan/lease losses	2,300,735	2,022,993	4,840,574	4,128,102
Loans/leases charged off	(1,524,275)	(851,604)	(1,960,733)	(1,744,230)
Recoveries on loans/leases previously charged off	236,014	126,093	309,507	215,312
Balance	37,545,076	33,356,632	37,545,076	33,356,632
Allowance for impaired loans/leases					$ 3,139,565	$ 3,043,319
Allowance for nonimpaired loans/leases					34,405,511	31,312,409
Less allowance for estimated losses on loans/leases	36,532,602	32,059,150	34,355,728	30,757,448	37,545,076	34,355,728
Impaired loans/leases					12,712,395	18,354,163
Nonimpaired loans/leases					3,093,189,063	2,938,359,330
Loans and Leases Receivable, Net of Deferred Income					$ 3,105,901,458	$ 2,956,713,493
Allowance as a percentage of impaired loans/leases					24.70%	16.58%
Allowance as a percentage of nonimpaired loans/leases					1.11%	1.07%
Total allowance as a percentage of total loans/leases					1.21%	1.16%
Commercial Portfolio Segment [Member]
Balance	15,065,245	12,954,090	14,323,036	12,545,110
Provision for loan/lease losses	777,013	1,281,786	1,585,174	1,875,144
Loans/leases charged off	(728,890)	(74,071)	(824,389)	(292,344)
Recoveries on loans/leases previously charged off	120,503	45,928	150,050	79,823
Balance	15,233,871	14,207,733	15,233,871	14,207,733
Allowance for impaired loans/leases					$ 308,091	$ 715,627
Allowance for nonimpaired loans/leases					14,925,780	13,607,409
Less allowance for estimated losses on loans/leases	15,065,245	12,954,090	14,323,036	12,545,110	15,233,871	14,323,036
Impaired loans/leases					1,551,445	6,248,209
Nonimpaired loans/leases					1,271,448,649	1,128,268,106
Loans and Leases Receivable, Net of Deferred Income					$ 1,273,000,094	$ 1,134,516,315
Allowance as a percentage of impaired loans/leases					19.86%	11.45%
Allowance as a percentage of nonimpaired loans/leases					1.17%	1.21%
Total allowance as a percentage of total loans/leases					1.20%	1.26%
Commercial Real Estate Portfolio Segment [Member]
Balance	14,938,020	12,643,266	13,962,688	11,670,609
Provision for loan/lease losses	871,475	339,857	1,836,858	1,306,128
Loans/leases charged off		(10,375)		(10,375)
Recoveries on loans/leases previously charged off	9,545	26,485	19,494	32,871
Balance	15,819,040	12,999,233	15,819,040	12,999,233
Allowance for impaired loans/leases					$ 2,109,374	$ 1,429,460
Allowance for nonimpaired loans/leases					13,709,666	12,533,228
Less allowance for estimated losses on loans/leases	14,938,020	12,643,266	13,962,688	11,670,609	15,819,040	13,962,688
Impaired loans/leases					6,967,425	6,529,262
Nonimpaired loans/leases					1,342,351,489	1,296,962,620
Loans and Leases Receivable, Net of Deferred Income					$ 1,349,318,914	$ 1,303,491,882
Allowance as a percentage of impaired loans/leases					30.27%	21.89%
Allowance as a percentage of nonimpaired loans/leases					1.02%	0.97%
Total allowance as a percentage of total loans/leases					1.17%	1.07%
Finance Leases Portfolio Segment [Member]
Balance	2,730,301	2,978,260	2,382,098	3,111,898
Provision for loan/lease losses	687,908	297,672	1,292,691	802,687
Loans/leases charged off	(794,299)	(684,079)	(1,078,186)	(1,342,763)
Recoveries on loans/leases previously charged off	100,445	46,448	127,752	66,479
Balance	2,724,355	2,638,301	2,724,355	2,638,301
Allowance for impaired loans/leases					$ 375,803	$ 504,469
Allowance for nonimpaired loans/leases					2,348,552	1,877,629
Less allowance for estimated losses on loans/leases	2,730,301	2,978,260	2,382,098	3,111,898	2,724,355	2,382,098
Impaired loans/leases					2,529,004	3,669,492
Nonimpaired loans/leases					130,667,609	137,778,740
Loans and Leases Receivable, Net of Deferred Income					$ 133,196,613	$ 141,448,232
Allowance as a percentage of impaired loans/leases					14.86%	13.75%
Allowance as a percentage of nonimpaired loans/leases					1.80%	1.36%
Total allowance as a percentage of total loans/leases					2.05%	1.68%
Residential Portfolio Segment [Member]
Balance	2,375,219	2,375,864	2,466,431	2,342,344
Provision for loan/lease losses	57,283	116,151	17,946	159,671
Loans/leases charged off		(61,561)	(52,325)	(75,184)
Recoveries on loans/leases previously charged off	600		1,050	3,623
Balance	2,433,102	2,430,454	2,433,102	2,430,454
Allowance for impaired loans/leases					$ 239,419	$ 355,167
Allowance for nonimpaired loans/leases					2,193,683	2,111,264
Less allowance for estimated losses on loans/leases	2,375,219	2,375,864	2,466,431	2,342,344	2,433,102	2,466,431
Impaired loans/leases					1,449,866	1,704,846
Nonimpaired loans/leases					255,983,847	256,941,419
Loans and Leases Receivable, Net of Deferred Income					$ 257,433,713	$ 258,646,265
Allowance as a percentage of impaired loans/leases					16.51%	20.83%
Allowance as a percentage of nonimpaired loans/leases					0.86%	0.82%
Total allowance as a percentage of total loans/leases					0.95%	0.95%
Consumer Portfolio Segment [Member]
Balance	1,423,817	1,107,670	1,221,475	1,087,487
Provision for loan/lease losses	(92,944)	(12,473)	107,905	(15,528)
Loans/leases charged off	(1,086)	(21,518)	(5,833)	(23,564)
Recoveries on loans/leases previously charged off	4,921	7,232	11,161	32,516
Balance	1,334,708	1,080,911	1,334,708	1,080,911
Allowance for impaired loans/leases					$ 106,878	$ 38,596
Allowance for nonimpaired loans/leases					1,227,830	1,182,879
Less allowance for estimated losses on loans/leases	$ 1,423,817	$ 1,107,670	$ 1,221,475	$ 1,087,487	1,334,708	1,221,475
Impaired loans/leases					214,655	202,354
Nonimpaired loans/leases					92,737,469	118,408,445
Loans and Leases Receivable, Net of Deferred Income					$ 92,952,124	$ 118,610,799
Allowance as a percentage of impaired loans/leases					49.79%	19.07%
Allowance as a percentage of nonimpaired loans/leases					1.32%	1.00%
Total allowance as a percentage of total loans/leases					1.44%	1.03%