Note 13 - Fair Value Measurements - Valuation and Unobservable Inputs for Level 3 Assets (Details) - Fair Value, Inputs, Level 3 [Member]	6 Months Ended
	Sep. 30, 2017 USD ($)
Investments [Member] | Market Approach Valuation Technique [Member]
Investment securities, fair value	$ 1,904,806
Investments [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Investment securities, discount rate	0.00%
Investments [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Investment securities, discount rate	10.00%
Impaired Loans [Member] | Market Approach Valuation Technique [Member]
Fair Value	$ 8,589,469
Impaired Loans [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Investment securities, discount rate	0.00%
Impaired Loans [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Investment securities, discount rate	25.00%
Impaired Loans [Member] | Income Approach Valuation Technique [Member] | Minimum [Member]
Investment securities, discount rate	2.63%
Impaired Loans [Member] | Income Approach Valuation Technique [Member] | Maximum [Member]
Investment securities, discount rate	7.25%
Foreclosed Real Estate [Member] | Market Approach Valuation Technique [Member]
Fair Value	$ 483,204
Foreclosed Real Estate [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Investment securities, discount rate	0.00%
Foreclosed Real Estate [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Investment securities, discount rate	25.00%
Premises and Equipment Held-for-sale [Member] | Market Approach Valuation Technique [Member]
Fair Value	$ 547,884
Premises and Equipment Held-for-sale [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Investment securities, discount rate	0.00%
Premises and Equipment Held-for-sale [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Investment securities, discount rate	10.00%