Note 5 - Loans Receivable and Allowance for Loan Losses - Past Due Loans (Details) - USD ($)		Jun. 30, 2018		Mar. 31, 2018		Jun. 30, 2017
Current		$ 369,328,138		$ 380,780,116
Past due		1,484,181		2,476,716
Nonaccrual loans		8,948,874		5,964,407
Loans		379,761,193		389,221,239
Nonaccrual interest not accrued		204,462		393,818
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		228,467		1,037,360
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		26,172		233,115
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		1,229,542		1,206,241
Real Estate Loans [Member]
Loans		302,982,355		309,465,974
Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		830,649		864,644
Nonaccrual interest not accrued		6,556		61,370
Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		157,728		752,982
Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		26,172		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		352,999		361,821
Nonaccrual interest not accrued		5,107		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		1,032,283		1,206,241
Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans		7,505,364		4,555,202
Loans		113,145,208		112,166,254
Nonaccrual interest not accrued		184,891		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		197,259
Real Estate Loans [Member] | Commercial Construction [Member]
Nonaccrual loans
Loans		3,404,832		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		240,009		165,285
Loans	[1]	38,967,140		40,143,965
Nonaccrual interest not accrued		7,462		12,891
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		14,573		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		19,210,772		19,995,789
Nonaccrual interest not accrued				436
Home Equity Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
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		19,853		4,850
Loans	[2]	18,600,926		19,615,511
Nonaccrual interest not accrued		446		385
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		56,166		148,876
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due				28,300
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Legacy Loans [Member]
Current		263,581,744		270,807,643
Past due		658,882		1,315,929
Nonaccrual loans		8,339,436		5,126,537
Loans		272,580,062	[3]	277,250,109	[3]	$ 229,776,396
Nonaccrual interest not accrued		196,016		325,094
Legacy Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		117,467		347,996
Legacy Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		26,172		233,115
Legacy Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		515,243		734,818
Legacy Loans [Member] | Real Estate Loans [Member]
Loans	[3]	203,921,602		206,141,595
Legacy Loans [Member] | Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		515,611		526,584
Loans		89,889,454				75,418,756
Nonaccrual interest not accrued		2,248		8,250
Legacy Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		74,733		63,618
Legacy Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		26,172		70,291
Legacy Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Legacy Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member]
Nonaccrual loans		58,599		60,949
Loans		8,822,670				7,811,461
Nonaccrual interest not accrued		969		8,513
Legacy Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Legacy Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Legacy Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		515,243		734,818
Legacy Loans [Member] | Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans		7,505,364		4,356,264
Loans		102,659,016	[3]	100,403,769	[3]	92,628,423
Nonaccrual interest not accrued		184,891		294,619
Legacy Loans [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Legacy Loans [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Legacy Loans [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Legacy Loans [Member] | Real Estate Loans [Member] | Commercial Construction [Member]
Nonaccrual loans
Loans		2,550,462	[3]	5,763,784	[3]	2,326,457
Nonaccrual interest not accrued
Legacy Loans [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Legacy Loans [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Legacy Loans [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Legacy Loans [Member] | Commercial Portfolio Segment [Member]
Nonaccrual loans		240,009		165,285
Loans		37,061,370	[1],[3]	38,302,739	[1],[3]	35,339,083
Nonaccrual interest not accrued		7,462		12,891
Legacy Loans [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		14,573		135,502
Legacy Loans [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due				134,524
Legacy Loans [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Legacy Loans [Member] | Home Equity Loans [Member]
Nonaccrual loans				12,605
Loans		13,735,464	[3]	13,956,327	[3]	14,116,647
Nonaccrual interest not accrued				436
Legacy Loans [Member] | Home Equity Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Legacy Loans [Member] | Home Equity Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Legacy Loans [Member] | Home Equity Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Legacy Loans [Member] | Consumer Portfolio Segment [Member]
Nonaccrual loans		19,853		4,850
Loans		17,861,626	[2],[3]	18,849,448	[2],[3]	2,135,569
Nonaccrual interest not accrued		446		385
Legacy Loans [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		28,161		148,876
Legacy Loans [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due				28,300
Legacy Loans [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Acquired Loans [Member]
Current		105,746,394		109,972,473
Past due		825,299		1,160,787
Nonaccrual loans		609,438		837,870
Loans		107,181,131		111,971,130		123,955,508
Nonaccrual interest not accrued		8,446		68,724
Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		111,000		689,364
Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		714,299		471,423
Acquired Loans [Member] | Real Estate Loans [Member]
Loans		99,060,753		103,324,379
Acquired Loans [Member] | Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		315,038		338,060
Loans		70,509,208				80,296,553
Nonaccrual interest not accrued		4,308		53,120
Acquired Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		82,995		689,364
Acquired Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Acquired Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Acquired Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member]
Nonaccrual loans		294,400		300,872
Loans		17,210,982				18,433,397
Nonaccrual interest not accrued		4,138		15,604
Acquired Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Acquired Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Acquired Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		517,040		471,423
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans				198,938
Loans		10,486,192		11,762,485		14,399,402
Nonaccrual interest not accrued
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		197,259
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial Construction [Member]
Nonaccrual loans
Loans		854,370		1,352,019		1,191,507
Nonaccrual interest not accrued
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial Construction [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Acquired Loans [Member] | Commercial Portfolio Segment [Member]
Nonaccrual loans
Loans		1,905,770	[1]	1,841,226	[1]	2,037,264
Nonaccrual interest not accrued
Acquired Loans [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Acquired Loans [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Acquired Loans [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Acquired Loans [Member] | Home Equity Loans [Member]
Nonaccrual loans
Loans		5,475,308		6,039,462		6,668,685
Nonaccrual interest not accrued
Acquired Loans [Member] | Home Equity Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Acquired Loans [Member] | Home Equity Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Acquired Loans [Member] | Home Equity Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Acquired Loans [Member] | Consumer Portfolio Segment [Member]
Nonaccrual loans
Loans		739,301		766,063	[2]	$ 928,700
Nonaccrual interest not accrued
Acquired Loans [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		28,005
Acquired Loans [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Acquired Loans [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".