Note 12 - Fair Value Measurement and Disclosure - Assets Measured at Fair Value on a Non-recurring Basis (Details) - Fair Value, Nonrecurring [Member] - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Foreclosed assets	$ 214,392	$ 78,926
Impaired loans, net	441,981	716,998
Fair Value, Inputs, Level 1 [Member]
Foreclosed assets	0
Impaired loans, net	0	0
Fair Value, Inputs, Level 2 [Member]
Foreclosed assets	0
Impaired loans, net	0	0
Fair Value, Inputs, Level 3 [Member]
Foreclosed assets	214,392	78,926
Impaired loans, net	$ 441,981	$ 716,998