Note 5 - Loans Receivable and Allowance for Loan Losses - Past Due Loans (Details) - USD ($)		Dec. 31, 2018		Mar. 31, 2018		Dec. 31, 2017
Current		$ 361,746,473		$ 380,780,116
Past due		1,283,570		2,476,716
Nonaccrual loans		5,195,677		5,964,407
Loans		368,225,720		389,221,239
Nonaccrual interest not accrued		280,718		393,818
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		288,461		1,037,360
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		659,595		233,115
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		335,514		1,206,241
Real Estate Loans [Member]
Loans		294,195,991		309,465,974
Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		666,140		864,644
Nonaccrual interest not accrued		9,526		61,370
Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		89,508		752,982
Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		193,600		70,291
Real Estate Loans [Member] | Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Real Estate Loans [Member] | Investor Loans [Member]
Nonaccrual loans		160,689		361,821
Nonaccrual interest not accrued		8,556		24,117
Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		29,357
Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		335,514		1,206,241
Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans		4,139,177		4,555,202
Loans		115,045,570		112,166,254
Nonaccrual interest not accrued		252,381		294,619
Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Real Estate Loans [Member] | Commercial Construction [Member]
Nonaccrual loans
Loans		2,602,530		7,115,803
Nonaccrual interest not accrued
Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member]
Nonaccrual loans		143,145		165,285
Loans	[1]	36,983,002		40,143,965
Nonaccrual interest not accrued		8,796		12,891
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		120,418		135,502
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		460,762		134,524
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Home Equity Loans [Member]
Nonaccrual loans		97		12,605
Loans		20,018,119		19,995,789
Nonaccrual interest not accrued				436
Home Equity Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		68
Home Equity Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Home Equity Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Consumer Portfolio Segment [Member]
Nonaccrual loans		86,429		4,850
Loans	[2]	17,028,608		19,615,511
Nonaccrual interest not accrued		1,459		385
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		49,110		148,876
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		5,233		28,300
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Originated [Member]
Current		262,125,497		270,807,643
Past due		975,652		1,315,929
Nonaccrual loans		4,766,113		5,126,537
Loans		267,867,262	[3]	277,250,109	[3]	$ 272,324,778
Nonaccrual interest not accrued		266,991		325,094
Financial Asset Originated [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		214,795		347,996
Financial Asset Originated [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		538,372		233,115
Financial Asset Originated [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		222,485		734,818
Financial Asset Originated [Member] | Real Estate Loans [Member]
Loans	[3]	201,184,464		206,141,595
Financial Asset Originated [Member] | Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		365,610		526,584
Loans		86,548,084				87,230,020
Nonaccrual interest not accrued		2,289		8,250
Financial Asset Originated [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		71,020		63,618
Financial Asset Originated [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		72,377		70,291
Financial Asset Originated [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Real Estate Loans [Member] | Investor Loans [Member]
Nonaccrual loans		31,752		60,949
Loans		7,337,281				7,375,997
Nonaccrual interest not accrued		2,066		8,513
Financial Asset Originated [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		222,485		734,818
Financial Asset Originated [Member] | Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans		4,139,177		4,356,264
Loans		105,755,786	[3]	100,403,769	[3]	100,857,452
Nonaccrual interest not accrued		252,381		294,619
Financial Asset Originated [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Real Estate Loans [Member] | Commercial Construction [Member]
Nonaccrual loans
Loans		1,543,313	[3]	5,763,784	[3]	3,995,441
Nonaccrual interest not accrued
Financial Asset Originated [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Commercial Portfolio Segment [Member]
Nonaccrual loans		143,145		165,285
Loans		35,276,493	[1],[3]	38,302,739	[1],[3]	38,988,229
Nonaccrual interest not accrued		8,796		12,891
Financial Asset Originated [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		120,418		135,502
Financial Asset Originated [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		460,762		134,524
Financial Asset Originated [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Home Equity Loans [Member]
Nonaccrual loans				12,605
Loans		15,077,068	[3]	13,956,327	[3]	13,802,091
Nonaccrual interest not accrued				436
Financial Asset Originated [Member] | Home Equity Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Home Equity Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Home Equity Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Originated [Member] | Consumer Portfolio Segment [Member]
Nonaccrual loans		86,429		4,850
Loans		16,329,237	[2],[3]	18,849,448	[2],[3]	20,075,548
Nonaccrual interest not accrued		1,459		385
Financial Asset Originated [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		23,357		148,876
Financial Asset Originated [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		5,233		28,300
Financial Asset Originated [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Acquired [Member]
Current		99,620,976		109,972,473
Past due		307,918		1,160,787
Nonaccrual loans		429,564		837,870
Loans		100,358,458		111,971,130		115,515,899
Nonaccrual interest not accrued		13,727		68,724
Financial Asset Acquired [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		73,666		689,364
Financial Asset Acquired [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		121,223
Financial Asset Acquired [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		113,029		471,423
Financial Asset Acquired [Member] | Real Estate Loans [Member]
Loans		93,011,527		103,324,379
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		300,530		338,060
Loans		66,255,260				74,701,711
Nonaccrual interest not accrued		7,237		53,120
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		18,488		689,364
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		121,223
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Investor Loans [Member]
Nonaccrual loans		128,937		300,872
Loans		16,407,265				18,208,906
Nonaccrual interest not accrued		6,490		15,604
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		29,357
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		113,029		471,423
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans				198,938
Loans		9,289,784		11,762,485		12,160,844
Nonaccrual interest not accrued
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Commercial Construction [Member]
Nonaccrual loans
Loans		1,059,217		1,352,019		856,970
Nonaccrual interest not accrued
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Commercial Portfolio Segment [Member]
Nonaccrual loans
Loans		1,706,509	[1]	1,841,226	[1]	1,928,232
Nonaccrual interest not accrued
Financial Asset Acquired [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Home Equity Loans [Member]
Nonaccrual loans		97
Loans		4,941,051		6,039,462		6,874,136
Nonaccrual interest not accrued
Financial Asset Acquired [Member] | Home Equity Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		68
Financial Asset Acquired [Member] | Home Equity Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Home Equity Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Consumer Portfolio Segment [Member]
Nonaccrual loans
Loans		699,372		766,063	[2]	$ 785,100
Nonaccrual interest not accrued
Financial Asset Acquired [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		25,753
Financial Asset Acquired [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Financial Asset Acquired [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due

[1] "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.

[2] "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.

[3] 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".