Note 12 - Fair Value Measurements - Securities Available for Sale Measured On a Recurring Basis (Details) - USD ($)	Sep. 30, 2018	Mar. 31, 2018
Investment securities available for sale, at fair value	$ 68,862,989	$ 75,404,136
Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	68,862,989	75,404,136
US Government Agencies Debt Securities [Member]
Investment securities available for sale, at fair value	2,711,667	2,718,649
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	2,711,667	2,718,649
US States and Political Subdivisions Debt Securities [Member]
Investment securities available for sale, at fair value	11,492,431	11,705,991
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	11,492,431	11,705,991
Corporate Debt Securities [Member]
Investment securities available for sale, at fair value	1,949,132	1,954,076
Corporate Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	1,949,132	1,954,076
Collateralized Mortgage Backed Securities [Member]
Investment securities available for sale, at fair value	52,709,759	59,025,420
Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	52,709,759	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	66,913,857	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	2,711,667	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	11,492,431	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	52,709,759	59,025,404
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	1,949,132	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	1,949,132	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