Note 12 - Fair Value Measurements - Measurements On Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($)	Jun. 30, 2018	Mar. 31, 2018
Impaired loans	$ 11,554,069	$ 8,454,083
Foreclosed real estate	457,778	457,778
Fair Value, Inputs, Level 1 [Member]
Impaired loans
Foreclosed real estate
Fair Value, Inputs, Level 2 [Member]
Impaired loans
Foreclosed real estate
Fair Value, Inputs, Level 3 [Member]
Impaired loans	11,554,069	8,454,083
Foreclosed real estate	$ 457,778	$ 457,778