Note 9 - Allowance for Loan Losses and Credit Quality Information - Purchased Loans Acquired Through Acquisition (Details)	3 Months Ended
	Jun. 30, 2018 USD ($)
Purchased performing loans:
Carrying Amount	$ 400,000
Purchased Performing Loans [Member]
Purchased performing loans:
Contractual Principle Receivable	9,447,000
Contractual Principle Receivable, change due to payments/refinances	(891,000)
Contractual Principle Receivable	8,556,000
Accretable Difference	(218,000)
Accretable Difference, change due to payments/refinances	12,000
Accretable Difference	(206,000)
Carrying Amount	9,229,000
Carrying Amount, change due to payments/refinances	(879,000)
Carrying Amount	8,350,000
Purchased Credit Impaired Loans [Member]
Purchased performing loans:
Contractual Principle Receivable	400,000
Contractual Principle Receivable, change due to payments/refinances	(4,000)
Contractual Principle Receivable	396,000
Non-accretable difference	(37,000)
Non-accretable difference, change due to payments/refinances	1,000
Non-accretable difference	(36,000)
Carrying Amount	363,000
Carrying Amount, change due to payments/refinances	(3,000)
Carrying Amount	$ 360,000