Note 8 - Fair Values of Financial Instruments - Assets at Fair Value (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Total, fair value	$ 61,374,800	$ 44,517,178
Assets, fair value disclosure	64,784,428	48,022,466
Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	61,374,800	44,517,178
Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure	3,409,628	3,505,288
Fair Value, Nonrecurring [Member]
Impaired loans, fair value disclosure	3,409,628	3,505,288
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Impaired loans, fair value disclosure	0	0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Impaired loans, fair value disclosure	0	0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Impaired loans, fair value disclosure	3,409,628	3,505,288
Asset-backed Securities [Member]
Total, fair value	34,524,563	31,018,748
Asset-backed Securities [Member] | Fair Value, Recurring [Member]
Total, fair value	34,524,563	31,018,748
Asset-backed Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total, fair value	0	0
Asset-backed Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total, fair value	34,524,563	31,018,748
Asset-backed Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total, fair value	0	0
US Government Agencies Debt Securities [Member]
Total, fair value	953,122	1,079,447
US Government Agencies Debt Securities [Member] | Fair Value, Recurring [Member]
Total, fair value	953,122	1,079,447
US Government Agencies Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total, fair value	0	0
US Government Agencies Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total, fair value	953,122	1,079,447
US Government Agencies Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total, fair value	0	0
US States and Political Subdivisions Debt Securities [Member]
Total, fair value	25,897,115	12,418,983
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member]
Total, fair value	25,897,115	12,418,983
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total, fair value	0	0
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total, fair value	25,897,115	12,418,983
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total, fair value	$ 0	$ 0