Note 7 - Fair Values of Financial Instruments - Significant Unobservable Inputs (Details)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Impaired loans, fair value disclosure	$ 5,344,477	$ 5,436,972
Commercial Real Estate Portfolio Segment [Member]
Impaired loans, fair value disclosure	3,571,208	3,483,078
One-to-four Family Residential Real Estate Portfolio Segment [Member]
Impaired loans, fair value disclosure	663,580	679,184
Commercial and Industrial Portfolio Segment [Member]
Impaired loans, fair value disclosure	1,109,689	1,274,710
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Impaired loans, fair value disclosure	5,344,477	5,436,972
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Valuation, Market Approach [Member] \| Commercial Real Estate Portfolio Segment [Member]
Impaired loans, fair value disclosure	$ 3,571,208	$ 3,483,078
Fair Value, Measurements, 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, Measurements, 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, Measurements, 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	$ 663,580	$ 679,184
Fair Value, Measurements, 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, Measurements, 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
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Valuation, Market Approach [Member] \| Commercial and Industrial Portfolio Segment [Member]
Impaired loans, fair value disclosure	$ 1,109,689	$ 1,274,710
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Valuation, Market Approach [Member] \| Commercial and Industrial Portfolio Segment [Member] \| Minimum [Member] \| Measurement Input, Discount Rate [Member]
Impaired loans, Unobservable input valuation	0.17	0.17
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Valuation, Market Approach [Member] \| Commercial and Industrial Portfolio Segment [Member] \| Maximum [Member] \| Measurement Input, Discount Rate [Member]
Impaired loans, Unobservable input valuation	0.18	0.18
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Internal Estimate [member]
Derivative IRLC's, fair value disclosure	$ 336,041
Fair Value, Measurements, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Internal Estimate [member] \| Measurement Input, Pull-through Rate [Member]
Derivative IRLC's, Unobservable input valuation	81

Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation, Market Approach [Member] | Commercial Real Estate Portfolio Segment [Member]

Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation, Market Approach [Member] | One-to-four Family Residential Real Estate Portfolio Segment [Member]

Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation, Market Approach [Member] | Commercial and Industrial Portfolio Segment [Member]

Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Internal Estimate [member]

Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Internal Estimate [member] | Measurement Input, Pull-through Rate [Member]