Note 7 - Deposits - Deposits (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Demand, weighted average rate	0.00%	0.01%
Demand, balance	$ 94,727,683	$ 80,910,910
Demand, percentage of deposits	15.60%	16.00%
NOW, weighted average rate	0.35%	0.30%
NOW, balance	$ 139,458,528	$ 129,137,807
NOW, percentage of deposits	23.00%	25.60%
Money market, weighted average rate	0.73%	0.45%
Money market, balance	$ 187,064,098	$ 155,529,796
Money market, percentage of deposits	30.80%	30.80%
Savings, weighted average rate	0.20%	0.20%
Savings, balance	$ 30,848,154	$ 28,095,248
Savings, percentage of deposits	5.50%	5.50%
Weighted average rate	0.62%	0.43%
Deposits	$ 607,364,350	$ 505,362,750
Percentage of deposits	100.00%	100.00%
Certificates, weighted average rate	1.20%	0.90%
Certificates, balance	$ 155,265,887	$ 111,688,989
Certificates, percentage of deposits	25.60%	22.10%
Deposits not Including Time Deposits [Member]
Weighted average rate	0.42%	0.29%
Deposits	$ 452,098,463	$ 393,673,761
Percentage of deposits	74.40%	77.90%
Certificates of Deposit, 0 to 0.99% [Member]
Certificates, weighted average rate	0.69%	0.54%
Certificates, balance	$ 46,771,850	$ 57,349,324
Certificates, percentage of deposits	7.70%	11.30%
Certificates Of Deposit 1 To 1.99% [Member]
Certificates, weighted average rate	1.39%	1.28%
Certificates, balance	$ 104,284,007	$ 54,319,296
Certificates, percentage of deposits	17.30%	10.80%
Certificates Of Deposit 2 To 3.99% [Member]
Certificates, weighted average rate	2.00%	2.14%
Certificates, balance	$ 4,210,030	$ 20,369
Certificates, percentage of deposits	0.70%	0.00%