Note 5 - Loans Receivable and Allowance for Loan Losses - Past Due Loans (Details) - USD ($)		Sep. 30, 2018		Mar. 31, 2018		Sep. 30, 2017
Current		$ 367,214,383		$ 380,780,116
Past due		1,689,113		2,476,716
Nonaccrual loans		5,745,369		5,964,407
Loans		374,648,865		389,221,239
Nonaccrual interest not accrued		276,939		393,818
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		635,248		1,037,360
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		716,120		233,115
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		337,745		1,206,241
Real Estate Loans [Member]
Loans		299,698,738		309,465,974
Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		702,498		864,644
Nonaccrual interest not accrued		7,865		61,370
Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		320,212		752,982
Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		687,347		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		420,518		361,821
Nonaccrual interest not accrued		9,731		24,117
Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
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		337,745		1,206,241
Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans		4,447,906		4,555,202
Loans		115,696,478		112,166,254
Nonaccrual interest not accrued		246,030		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		3,457,168		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		160,000
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		167,239		165,285
Loans	[1]	37,889,576		40,143,965
Nonaccrual interest not accrued		13,166		12,891
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due				135,502
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due				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				12,605
Loans		19,367,708		19,995,789
Nonaccrual interest not accrued				436
Home Equity Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		33,031
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		7,208		4,850
Loans	[2]	17,692,843		19,615,511
Nonaccrual interest not accrued		147		385
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		122,005		148,876
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		28,773		28,300
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Financial Asset Originated [Member]
Current		264,810,304		270,807,643
Past due		416,282		1,315,929
Nonaccrual loans		4,882,382		5,126,537
Loans		270,108,968	[3]	277,250,109	[3]	$ 249,358,443
Nonaccrual interest not accrued		261,927		325,094
Financial Asset Originated [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		153,883		347,996
Financial Asset Originated [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		38,103		233,115
Financial Asset Originated [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		224,296		734,818
Financial Asset Originated [Member] | Real Estate Loans [Member]
Loans	[3]	202,817,744		206,141,595
Financial Asset Originated [Member] | Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		397,300		526,584
Loans		86,729,410				74,806,476
Nonaccrual interest not accrued		2,068		8,250
Financial Asset Originated [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		85,928		63,618
Financial Asset Originated [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		9,330		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		59,426		60,949
Loans		7,880,161				9,627,329
Nonaccrual interest not accrued		1,475		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		224,296		734,818
Financial Asset Originated [Member] | Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans		4,251,209		4,356,264
Loans		105,679,013	[3]	100,403,769	[3]	94,957,970
Nonaccrual interest not accrued		245,071		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		2,529,160	[3]	5,763,784	[3]	2,081,647
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		167,239		165,285
Loans		36,134,376	[1],[3]	38,302,739	[1],[3]	34,042,543
Nonaccrual interest not accrued		13,166		12,891
Financial Asset Originated [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due				135,502
Financial Asset Originated [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due				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		14,183,532	[3]	13,956,327	[3]	13,664,414
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		7,208		4,850
Loans		16,973,316	[2],[3]	18,849,448	[2],[3]	20,178,064
Nonaccrual interest not accrued		147		385
Financial Asset Originated [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		67,955		148,876
Financial Asset Originated [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		28,773		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		102,404,079		109,972,473
Past due		1,272,831		1,160,787
Nonaccrual loans		862,987		837,870
Loans		104,539,897		111,971,130		118,290,856
Nonaccrual interest not accrued		15,012		68,724
Financial Asset Acquired [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		481,365		689,364
Financial Asset Acquired [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		678,017
Financial Asset Acquired [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		113,449		471,423
Financial Asset Acquired [Member] | Real Estate Loans [Member]
Loans		96,880,994		103,324,379
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		305,198		338,060
Loans		68,932,853				77,663,426
Nonaccrual interest not accrued		5,797		53,120
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		234,284		689,364
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		678,017
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		361,092		300,872
Loans		17,002,667				18,423,892
Nonaccrual interest not accrued		8,256		15,604
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
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		113,449		471,423
Financial Asset Acquired [Member] | Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans		196,697		198,938
Loans		10,017,465		11,762,485		12,114,557
Nonaccrual interest not accrued		959
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		928,008		1,352,019		1,058,534
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		160,000
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		1,755,200	[1]	1,841,226	[1]	1,668,783
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
Loans		5,184,176		6,039,462		6,459,424
Nonaccrual interest not accrued
Financial Asset Acquired [Member] | Home Equity Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		33,031
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		719,528		766,063	[2]	$ 902,240
Nonaccrual interest not accrued
Financial Asset Acquired [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		54,050
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".