Note 12 - Fair Value Measurements - Derivatives Measured On a Recurring Basis (Details) - USD ($)	Sep. 30, 2018	Mar. 31, 2018
Offsetting Commercial Real Estate Loan by Interest Rate Swap [Member] \| Loans and Leases [Member]
Commercial real estate loan, fair value	$ 2,927,163	$ 3,022,744
Offsetting Commercial Real Estate Loan by Interest Rate Swap [Member] \| Loans and Leases [Member] \| Fair Value, Measurements, Recurring [Member]
Loans - Commercial real estate loan	2,927,163	3,022,744
Interest Rate Swap [Member]
Loans - Commercial real estate loan	412,230	217,464
Interest Rate Swap [Member] \| Other Liabilities [Member] \| Fair Value, Measurements, Recurring [Member]
Commercial real estate loan, fair value	122,377	69,148
Derivatives - Interest rate swaps designated as cash flow hedge	412,230	217,464
Fair Value, Inputs, Level 1 [Member] \| Offsetting Commercial Real Estate Loan by Interest Rate Swap [Member] \| Loans and Leases [Member] \| Fair Value, Measurements, Recurring [Member]
Loans - Commercial real estate loan
Fair Value, Inputs, Level 1 [Member] \| Interest Rate Swap [Member] \| Other Liabilities [Member] \| Fair Value, Measurements, Recurring [Member]
Commercial real estate loan, fair value
Derivatives - Interest rate swaps designated as cash flow hedge
Fair Value, Inputs, Level 2 [Member] \| Offsetting Commercial Real Estate Loan by Interest Rate Swap [Member] \| Loans and Leases [Member] \| Fair Value, Measurements, Recurring [Member]
Loans - Commercial real estate loan	2,927,163	3,022,744
Fair Value, Inputs, Level 2 [Member] \| Interest Rate Swap [Member] \| Other Liabilities [Member] \| Fair Value, Measurements, Recurring [Member]
Commercial real estate loan, fair value	122,377	69,148
Derivatives - Interest rate swaps designated as cash flow hedge	412,230	217,464
Fair Value, Inputs, Level 3 [Member] \| Offsetting Commercial Real Estate Loan by Interest Rate Swap [Member] \| Loans and Leases [Member] \| Fair Value, Measurements, Recurring [Member]
Loans - Commercial real estate loan
Fair Value, Inputs, Level 3 [Member] \| Interest Rate Swap [Member] \| Other Liabilities [Member] \| Fair Value, Measurements, Recurring [Member]
Commercial real estate loan, fair value
Derivatives - Interest rate swaps designated as cash flow hedge

Fair value of all asset derivatives designated as cash flow hedging instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Fair value of all derivative assets designated as fair value hedging instruments.

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