Note 1 - Nature of Operations and Summary of Significant Accounting Policies (Details Textual)				9 Months Ended
	May 13, 2016 USD ($) $ / shares	Sep. 11, 2015 USD ($) $ / shares	Oct. 10, 2012 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)	Mar. 31, 2016 shares
Common Stock, Shares, Issued | shares			3,703,000	3,413,646		3,413,646
Share Price | $ / shares			$ 10
Proceeds from Issuance of Common Stock			$ 35,580,000
Noninterest Expense Offering Cost			$ 1,450,000
Employee Stock Option Plan, Subscribed Percentage			8.00%
Employee Stock Ownership Plan (ESOP), Number of Allocated Shares | shares			296,240
Number of Branches				7
Fraternity Community Bancorp, Inc. [Member]
Business Acquisition, Share Price | $ / shares	$ 19.25
Payments to Acquire Businesses, Gross	$ 25,700,000			$ 25,704,871
Fairmount Bancorp, Inc. [Member]
Business Acquisition, Share Price | $ / shares		$ 30
Payments to Acquire Businesses, Gross		$ 14,200,000			$ 14,192,370