Note 3 - Securities - Securities in a Continuous Unrealized Loss Position (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 62,887,238	$ 79,361,229
Securities, continuous unrealized loss position, fair value	62,887,238	79,361,229
Securities, continuous unrealized loss position, unrealized losses	(1,005,224)	(2,217,205)
Securities, continuous unrealized loss position, less than 12 months, fair value	55,574,747	74,651,451
Securities, continuous unrealized loss position, less than 12 months, fair value	55,574,747	74,651,451
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(818,702)	(2,108,360)
Securities, continuous unrealized loss position, 12 months or more, fair value	7,312,491	4,709,778
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	(186,522)	(108,845)
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	20,841,731	33,264,218
Securities, continuous unrealized loss position, fair value	20,841,731	33,264,218
Securities, continuous unrealized loss position, unrealized losses	(368,313)	(1,085,654)
Securities, continuous unrealized loss position, less than 12 months, fair value	19,268,849	33,084,816
Securities, continuous unrealized loss position, less than 12 months, fair value	19,268,849	33,084,816
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(306,515)	(1,082,021)
Securities, continuous unrealized loss position, 12 months or more, fair value	1,572,882	179,402
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	(61,798)	(3,633)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	42,045,507	43,219,739
Securities, continuous unrealized loss position, fair value	42,045,507	43,219,739
Securities, continuous unrealized loss position, unrealized losses	(636,911)	(1,127,037)
Securities, continuous unrealized loss position, less than 12 months, fair value	36,305,898	39,570,463
Securities, continuous unrealized loss position, less than 12 months, fair value	36,305,898	39,570,463
Securities, continuous unrealized loss position, less than 12 months, unrealized losses	(512,187)	(1,022,511)
Securities, continuous unrealized loss position, 12 months or more, fair value	5,739,609	3,649,276
Securities, continuous unrealized loss position, 12 months or more, unrealized losses	$ (124,724)	(104,526)
Corporate Debt Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,877,272
Securities, continuous unrealized loss position, fair value		2,877,272
Securities, continuous unrealized loss position, unrealized losses		(4,514)
Securities, continuous unrealized loss position, less than 12 months, fair value		1,996,172
Securities, continuous unrealized loss position, less than 12 months, fair value		1,996,172
Securities, continuous unrealized loss position, less than 12 months, unrealized losses		(3,828)
Securities, continuous unrealized loss position, 12 months or more, fair value		881,100
Securities, continuous unrealized loss position, 12 months or more, unrealized losses		$ (686)