Note 8 - Fair Values of Financial Instruments - Significant Unobservable Inputs (Details)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Impaired loans, fair value disclosure	$ 3,409,628	$ 3,505,288
Impaired loans, fair value disclosure	3,409,628	3,505,288
Commercial Real Estate Portfolio Segment [Member]
Impaired loans, fair value disclosure	2,642,676	2,718,731
Impaired loans, fair value disclosure	2,642,676	2,718,731
One-to-four Family Residential Real Estate Portfolio Segment [Member]
Impaired loans, fair value disclosure	766,952	786,557
Impaired loans, fair value disclosure	766,952	786,557
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Impaired loans, fair value disclosure	3,409,628	3,505,288
Impaired loans, fair value disclosure	3,409,628	3,505,288
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation, Market Approach [Member] | Commercial Real Estate Portfolio Segment [Member]
Impaired loans, fair value disclosure	2,642,676	2,718,731
Impaired loans, fair value disclosure	$ 2,642,676	$ 2,718,731
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation, Market Approach [Member] | Commercial Real Estate Portfolio Segment [Member] | Minimum [Member] | Measurement Input, Discount Rate [Member]
Impaired loans, Unobservable input valuation	0.17	0.17
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation, Market Approach [Member] | Commercial Real Estate Portfolio Segment [Member] | Maximum [Member] | Measurement Input, Discount Rate [Member]
Impaired loans, Unobservable input valuation	0.18	0.18
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation, Market Approach [Member] | One-to-four Family Residential Real Estate Portfolio Segment [Member]
Impaired loans, fair value disclosure	$ 766,952	$ 786,557
Impaired loans, fair value disclosure	$ 766,952	$ 786,557
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation, Market Approach [Member] | One-to-four Family Residential Real Estate Portfolio Segment [Member] | Minimum [Member] | Measurement Input, Discount Rate [Member]
Impaired loans, Unobservable input valuation	0.17	0.17
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation, Market Approach [Member] | One-to-four Family Residential Real Estate Portfolio Segment [Member] | Maximum [Member] | Measurement Input, Discount Rate [Member]
Impaired loans, Unobservable input valuation	0.18	0.18