Note 21 - Unaudited Quarterly Operating Results - Quarterly Financial Data (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest income	$ 6,625,664	$ 6,354,303	$ 6,204,314	$ 6,205,045	$ 6,286,396	$ 6,229,091	$ 6,386,510	$ 6,287,637	$ 25,389,326	$ 25,189,634	$ 25,014,314
Interest expense	1,068,638	1,056,181	1,026,782	1,025,411	1,029,155	1,046,661	1,112,376	1,091,690	4,177,012	4,279,882	4,329,305
Net interest income	5,557,026	5,298,122	5,177,532	5,179,634	5,257,241	5,182,430	5,274,134	5,195,947	21,212,314	20,909,752	20,685,009
Provision for loan losses	425,000	200,000	375,000	375,000	250,000	200,000		150,000	1,375,000	600,000	1,275,000
Gain on loans and investment securities	544,172	658,205	525,644	470,456	356,351	416,177	820,828	334,910
Other noninterest income, net	722,299	657,296	653,769	638,366	586,089	693,782	654,089	615,846
Noninterest expense	4,364,169	4,317,707	4,309,394	4,109,476	3,964,059	4,052,003	4,514,944	4,078,722	17,100,746	16,609,728	14,864,924
Income before income taxes	2,034,328	2,095,916	1,672,551	1,803,980	1,985,622	2,040,386	2,234,107	1,917,981	7,606,775	8,178,096	7,895,204
Provision for income taxes	514,981	554,009	416,399	527,375	554,983	621,751	696,158	588,437	2,012,764	2,461,329	2,112,508
Net income available to common shareholders	$ 1,519,347	$ 1,541,907	$ 1,256,152	$ 1,276,605	$ 1,430,639	$ 1,418,635	$ 1,537,949	$ 1,329,544	$ 5,594,011	$ 5,716,767	$ 5,425,486
Basic income per common share (in dollars per share)	$ 0.35	$ 0.35	$ 0.29	$ 0.29	$ 0.33	$ 0.33	$ 0.35	$ 0.31	$ 1.28	$ 1.32	$ 1.35
Diluted income per common share (in dollars per share)	$ 0.34	$ 0.35	$ 0.28	$ 0.29	$ 0.33	$ 0.32	$ 0.35	$ 0.30	$ 1.27	$ 1.30	$ 1.33