Note 5 - Loans Receivable and Allowance for Loan Losses - Loans Receivable Excluding Loans Held for Sale (Details) - USD ($)		Sep. 30, 2018		Mar. 31, 2018		Sep. 30, 2017
Loans		$ 374,648,865		$ 389,221,239
Percentage of loans		100.00%		100.00%
Net deferred loan origination fees and costs		$ (194,146)		$ (212,746)
Loan premium (discount)		1,484,985		1,412,392
Net loans		375,939,704		390,420,885
Financial Asset Originated [Member]
Loans		270,108,968	[1]	277,250,109	[1]	$ 249,358,443
Net deferred loan origination fees and costs	[1]	(194,146)		(212,746)
Loan premium (discount)	[1]	1,773,078		1,922,428
Net loans	[1]	271,687,900		278,959,791
Financial Asset Acquired [Member]
Loans		104,539,897		111,971,130		118,290,856
Net deferred loan origination fees and costs
Loan premium (discount)		(288,093)		(510,036)
Net loans		104,251,804		111,461,094
Real Estate Loans [Member]
Loans		$ 299,698,738		$ 309,465,974
Percentage of loans		80.00%		80.00%
Real Estate Loans [Member] | Financial Asset Originated [Member]
Loans	[1]	$ 202,817,744		$ 206,141,595
Real Estate Loans [Member] | Financial Asset Acquired [Member]
Loans		96,880,994		103,324,379
Real Estate Loans [Member] | One to four family, Residential [Member]
Loans	[2]	$ 152,023,124		$ 157,997,250
Percentage of loans	[2]	40.00%		41.00%
Real Estate Loans [Member] | One to four family, Residential [Member] | Financial Asset Originated [Member]
Loans	[1],[2]	$ 83,090,271		$ 85,248,184
Real Estate Loans [Member] | One to four family, Residential [Member] | Financial Asset Acquired [Member]
Loans	[2]	68,932,853		72,749,066
Real Estate Loans [Member] | One to four family, Residential construction [Member]
Loans		$ 3,639,139		$ 5,450,827
Percentage of loans		1.00%		1.00%
Real Estate Loans [Member] | One to four family, Residential construction [Member] | Financial Asset Originated [Member]
Loans	[1]	$ 3,639,139		$ 5,450,827
Real Estate Loans [Member] | One to four family, Residential construction [Member] | Financial Asset Acquired [Member]
Loans
Real Estate Loans [Member] | One to four family, Investor [Member]
Loans	[3]	$ 24,882,829		$ 26,735,840
Percentage of loans	[3]	7.00%		7.00%
Real Estate Loans [Member] | One to four family, Investor [Member] | Financial Asset Originated [Member]
Loans	[1],[3]	$ 7,880,161		$ 9,275,031
Real Estate Loans [Member] | One to four family, Investor [Member] | Financial Asset Acquired [Member]
Loans	[3]	17,002,668		17,460,809
Real Estate Loans [Member] | Commercial [Member]
Loans		$ 115,696,478		$ 112,166,254
Percentage of loans		31.00%		29.00%
Real Estate Loans [Member] | Commercial [Member] | Financial Asset Originated [Member]
Loans		$ 105,679,013	[1]	$ 100,403,769	[1]	94,957,970
Real Estate Loans [Member] | Commercial [Member] | Financial Asset Acquired [Member]
Loans		10,017,465		11,762,485		12,114,557
Real Estate Loans [Member] | Commercial Construction [Member]
Loans		$ 3,457,168		$ 7,115,803
Percentage of loans		1.00%		2.00%
Real Estate Loans [Member] | Commercial Construction [Member] | Financial Asset Originated [Member]
Loans		$ 2,529,160	[1]	$ 5,763,784	[1]	2,081,647
Real Estate Loans [Member] | Commercial Construction [Member] | Financial Asset Acquired [Member]
Loans		928,008		1,352,019		1,058,534
Commercial Portfolio Segment [Member]
Loans	[4]	$ 37,889,576		$ 40,143,965
Percentage of loans	[4]	10.00%		10.00%
Commercial Portfolio Segment [Member] | Financial Asset Originated [Member]
Loans		$ 36,134,376	[1],[4]	$ 38,302,739	[1],[4]	34,042,543
Commercial Portfolio Segment [Member] | Financial Asset Acquired [Member]
Loans		1,755,200	[4]	1,841,226	[4]	1,668,783
Home Equity Loans [Member]
Loans		$ 19,367,708		$ 19,995,789
Percentage of loans		5.00%		5.00%
Home Equity Loans [Member] | Financial Asset Originated [Member]
Loans		$ 14,183,532	[1]	$ 13,956,327	[1]	13,664,414
Home Equity Loans [Member] | Financial Asset Acquired [Member]
Loans		5,184,176		6,039,462		6,459,424
Consumer Portfolio Segment [Member]
Loans	[5]	$ 17,692,843		$ 19,615,511
Percentage of loans	[5]	5.00%		5.00%
Consumer Portfolio Segment [Member] | Financial Asset Originated [Member]
Loans		$ 16,973,316	[1],[5]	$ 18,849,448	[1],[5]	20,178,064
Consumer Portfolio Segment [Member] | Financial Asset Acquired [Member]
Loans		$ 719,528		$ 766,063	[5]	$ 902,240

[1] As a result of the acquisition of Fraternity Community Bancorp, Inc., the parent company of Fraternity Federal Savings and Loan, in May 2016 and Fairmount Bancorp, Inc., the parent company of Fairmount Bank, in September 2015, we have segmented the portfolio into two components, loans originated by Hamilton Bank "Legacy" and loans acquired from Fraternity Community Bancorp, Inc. and Fairmount Bancorp, Inc. "Acquired".

[2] "Legacy" one-to four-family residential real estate loans at March 31, 2018 includes $19.2 million of various loan pools purchased in the second half of fiscal 2018.

[3] "Investor" loans are residential mortgage loans secured by non-owner occupied one-to four-family properties.

[4] "Legacy" commercial business loans at March 31, 2018 includes a $15.5 million pool of commercial lease loans purchased in June 2017 and $3.2 million in guaranteed SBA loans purchased in second half of fiscal 2018.

[5] "Legacy" consumer loans at March 31, 2018 includes $19.9 million of purchased loan pools consisting of recreational vehicles that were purchased in August and December 2017.