Note 3 - Acquisitions (Details Textual)			6 Months Ended	11 Months Ended	12 Months Ended
	May 13, 2016 USD ($) $ / shares	Sep. 11, 2015 USD ($) $ / shares	Mar. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)		Sep. 11, 2016 USD ($)	Mar. 31, 2016 USD ($)		Apr. 15, 2015 $ / shares
Professional and Contract Services Expense					$ 1,046,450			$ 383,125
Core Deposits [Member]
Finite-lived Intangible Assets Acquired		$ 543,000			$ 242,020	[1]		542,540	[2]
Finite-Lived Intangible Asset, Useful Life	8 years	8 years			8 years
Business Combination, Acquisition Related Costs		$ 1,300,000
Fraternity Community Bancorp, Inc. [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition	$ 108,872,041
Certain Loans Acquired in Transfer, Nonaccretable Difference	314,484
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Cash Flows Expected to be Collected at Acquisition	108,557,557
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable FMV Adjustment	$ 246,626
Business Acquisition, Share Price | $ / shares	$ 19.25
Payments to Acquire Businesses, Gross	$ 25,700,000				$ 25,704,871
Effective Income Tax Rate Reconciliation, Percent	39.45%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tangible Assets, Net	$ 23.60
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	242,020
Business Combination, Acquisition Related Costs	3,000,000			$ 1,100,000
Fraternity Community Bancorp, Inc. [Member] | Performing Financial Instruments [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition	107,474,993
Certain Loans Acquired in Transfer, Nonaccretable Difference
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Cash Flows Expected to be Collected at Acquisition	107,474,993
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable FMV Adjustment	$ 301,672
Fraternity Community Bancorp, Inc. [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Impaired, Number of Contracts	23
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition	$ 1,397,048
Certain Loans Acquired in Transfer, Nonaccretable Difference	314,484
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Cash Flows Expected to be Collected at Acquisition	1,082,564
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable FMV Adjustment	(55,046)
Fraternity Community Bancorp, Inc. [Member] | Core Deposits [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 242,020
Fairmount Bancorp, Inc. [Member]
Business Acquisition, Share Price | $ / shares		$ 30								$ 30
Payments to Acquire Businesses, Gross		$ 14,200,000						14,192,370
Effective Income Tax Rate Reconciliation, Percent		39.45%
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred							$ 215,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tangible Assets, Net		$ 9,600,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		$ 542,540
Business Combination, Acquisition Related Costs					$ 0			$ 510,000
Fraternity Community Bancorp, Inc. and Fairmount Bancorp, Inc. [Member] | Noncompete Agreements [Member]
Professional and Contract Services Expense			$ 532,000
Fraternity Community Bancorp, Inc. and Fairmount Bancorp, Inc. [Member] | Noncompete Agreements [Member] | Minimum [Member]
Finite-Lived Intangible Asset, Useful Life					1 year
Fraternity Community Bancorp, Inc. and Fairmount Bancorp, Inc. [Member] | Noncompete Agreements [Member] | Maximum [Member]
Finite-Lived Intangible Asset, Useful Life					2 years
Fraternity Community Bancorp, Inc. and Fairmount Bancorp, Inc. [Member] | Contract-Based Intangible Assets [Member]
Finite-Lived Intangible Asset, Useful Life					6 years
Professional and Contract Services Expense			$ 80,000

[1] Additions to intangible assets are related to the acquisition of Fraternity Community Bancorp, Inc.

[2] Additions to intangibles are related to the acquisition of Fairmount Bancorp, Inc.