Note 12 - Fair Value Measurements - Securities Available for Sale Measured On a Recurring Basis (Details) - USD ($)	Jun. 30, 2018	Mar. 31, 2018
Investment securities available for sale, at fair value	$ 72,638,697	$ 75,404,136
Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	72,638,697	75,404,136
US Government Agencies Debt Securities [Member]
Investment securities available for sale, at fair value	2,715,652	2,718,649
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	2,715,652	2,718,649
US States and Political Subdivisions Debt Securities [Member]
Investment securities available for sale, at fair value	11,632,843	11,705,991
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	11,632,843	11,705,991
Corporate Debt Securities [Member]
Investment securities available for sale, at fair value	1,983,250	1,954,076
Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	1,983,250	1,954,076
Collateralized Mortgage Backed Securities [Member]
Investment securities available for sale, at fair value	56,306,952	59,025,420
Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	56,306,952	59,025,420
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 1 [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	70,655,447	73,450,044
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	2,715,652	2,718,649
Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	11,632,843	11,705,991
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	56,306,952	59,025,404
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	1,983,250	1,954,092
Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	1,983,250	1,954,076
Fair Value, Inputs, Level 3 [Member] | Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value		$ 16