Note 2 - Investment Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Due in one year or less	$ 8,580,563
Due in one year or less	8,580,930
Due after one year through five years	16,946,533
Due after one year through five years	17,027,273
Due after five years	281,166,967
Due after five years	278,588,803
	306,694,063
	304,197,006	$ 320,414,899
Due in one year or less	3,228,439
Due in one year or less	3,240,004
Due after one year through five years	43,980,525
Due after one year through five years	44,165,961
Due after five years	51,615,976
Due after five years	51,281,990
	98,824,940
	98,687,955
	252,850,093
	250,952,021
Callable Securities [Member]
	44,660,147
	44,463,985
US States and Political Subdivisions Debt Securities [Member]
	303,147,006	319,364,899
US States and Political Subdivisions Debt Securities [Member] | Callable Securities [Member]
Amortized Cost	39,611,651
Fair Value	39,404,492
US Government-sponsored Enterprises Debt Securities [Member] | Callable Securities [Member]
Amortized Cost	5,048,496
Fair Value	5,059,493
Residential Mortgage Backed Securities [Member]
Amortized Cost	149,968,905
Fair Value	147,503,987
Other Securities [Member]
	1,050,000	$ 1,050,000
Amortized Cost	4,056,248
Fair Value	4,760,079
Callable Securities [Member] | US States and Political Subdivisions Debt Securities [Member]
Amortized Cost	163,299,673
Fair Value	$ 161,458,045