Note 4 - Securities - Securities Held-to-maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018
Securities held-to-maturity, amortized costs	$ 118,662	$ 122,905
Securities held-to-maturity, gross unrealized gains		2,301
Securities held-to-maturity, gross unrealized losses		657
Securities held-to-maturity, fair values	$ 119,790	124,549
US Government Agencies Debt Securities [Member]
Securities held-to-maturity, amortized costs		3,934
Securities held-to-maturity, gross unrealized gains		99
Securities held-to-maturity, gross unrealized losses		1
Securities held-to-maturity, fair values		4,032
US States and Political Subdivisions Debt Securities [Member]
Securities held-to-maturity, amortized costs		117,791
Securities held-to-maturity, gross unrealized gains		2,184
Securities held-to-maturity, gross unrealized losses		649
Securities held-to-maturity, fair values		119,326
Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized costs		196
Securities held-to-maturity, gross unrealized gains		18
Securities held-to-maturity, gross unrealized losses
Securities held-to-maturity, fair values		214
Corporate Debt Securities [Member]
Securities held-to-maturity, amortized costs		984
Securities held-to-maturity, gross unrealized gains
Securities held-to-maturity, gross unrealized losses		7
Securities held-to-maturity, fair values		$ 977

Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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- Definition

Amount, before other-than-temporary impairment (OTTI) accretion, of investment in debt securities measured at amortized cost (held-to-maturity).

+ References

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- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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