Note 4 - Loans and Allowance for Loan Losses - Troubled Debt Restructurings (Details)	3 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Number of loans	2
Pre-modification outstanding recorded balance	$ 510,420
Post-modification outstanding recorded balance	414,515
TDRs, carrying balance	11,836,998	$ 11,742,351
Interest Rate [Member]
Post-modification outstanding recorded balance	0
Term [Member]
Post-modification outstanding recorded balance	0
Combination [Member]
Post-modification outstanding recorded balance	$ 414,515
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member]
Number of loans	0
Pre-modification outstanding recorded balance	$ 0
Post-modification outstanding recorded balance	0
TDRs, carrying balance	1,248,510	1,290,462
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member] | Interest Rate [Member]
Post-modification outstanding recorded balance	0
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member] | Term [Member]
Post-modification outstanding recorded balance	0
Residential Portfolio Segment [Member] | Real Estate Residential, One To Four Family Units [Member] | Combination [Member]
Post-modification outstanding recorded balance	$ 0
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member]
Number of loans	0
Pre-modification outstanding recorded balance	$ 0
Post-modification outstanding recorded balance	0
TDRs, carrying balance
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member] | Interest Rate [Member]
Post-modification outstanding recorded balance	0
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member] | Term [Member]
Post-modification outstanding recorded balance	0
Residential Portfolio Segment [Member] | Real Estate Residential, Multi Family Units [Member] | Combination [Member]
Post-modification outstanding recorded balance	$ 0
Real Estate, Construction [Member]
Number of loans	0
Pre-modification outstanding recorded balance	$ 0
Post-modification outstanding recorded balance	0
TDRs, carrying balance	4,354,410	4,452,409
Real Estate, Construction [Member] | Interest Rate [Member]
Post-modification outstanding recorded balance	0
Real Estate, Construction [Member] | Term [Member]
Post-modification outstanding recorded balance	0
Real Estate, Construction [Member] | Combination [Member]
Post-modification outstanding recorded balance	$ 0
Commercial Real Estate Portfolio Segment [Member]
Number of loans	0
Pre-modification outstanding recorded balance	$ 0
Post-modification outstanding recorded balance	0
TDRs, carrying balance	5,653,777	5,666,096
Commercial Real Estate Portfolio Segment [Member] | Interest Rate [Member]
Post-modification outstanding recorded balance	0
Commercial Real Estate Portfolio Segment [Member] | Term [Member]
Post-modification outstanding recorded balance	0
Commercial Real Estate Portfolio Segment [Member] | Combination [Member]
Post-modification outstanding recorded balance	$ 0
Commercial Portfolio Segment [Member]
Number of loans	2
Pre-modification outstanding recorded balance	$ 510,420
Post-modification outstanding recorded balance	414,515
TDRs, carrying balance	580,301	214,529
Commercial Portfolio Segment [Member] | Interest Rate [Member]
Post-modification outstanding recorded balance	0
Commercial Portfolio Segment [Member] | Term [Member]
Post-modification outstanding recorded balance	0
Commercial Portfolio Segment [Member] | Combination [Member]
Post-modification outstanding recorded balance	$ 414,515
Consumer and Other Loans [Member]
Number of loans	0
Pre-modification outstanding recorded balance	$ 0
Post-modification outstanding recorded balance	0
TDRs, carrying balance		$ 118,855
Consumer and Other Loans [Member] | Interest Rate [Member]
Post-modification outstanding recorded balance	0
Consumer and Other Loans [Member] | Term [Member]
Post-modification outstanding recorded balance	0
Consumer and Other Loans [Member] | Combination [Member]
Post-modification outstanding recorded balance	$ 0