Note 6 - Loans Receivable and Allowance for Loan Losses - Past Due Loans (Details) - USD ($)		Sep. 30, 2017		Mar. 31, 2017		Sep. 30, 2016
Current		$ 359,961,450		$ 336,098,044
Past due		2,199,808		599,853
Nonaccrual loans		5,488,041		2,301,935
Ending balance, loans		367,649,299		338,999,832
Nonaccrual interest not accrued		51,489		182,113
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		1,578,978		504,192
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		212,383		74,631
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		408,447		21,030
Real Estate Loans [Member]
Ending balance, loans		290,733,831		293,721,660
Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		760,632		675,017
Nonaccrual interest not accrued		45,526		41,637
Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		1,387,277		69,618
Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		157,582		74,631
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		5,293		71,107
Nonaccrual interest not accrued		5,914		30,275
Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due				320,971
Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		54,801
Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		408,447		21,030
Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans		4,707,655		1,546,812
Ending balance, loans		107,072,527		107,564,212
Nonaccrual interest not accrued				109,818
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
Ending balance, loans		3,140,181		3,190,193
Nonaccrual interest not accrued
Real Estate Loans [Member] | Commercial construction [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due				113,603
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
Ending balance, loans		35,711,326		21,537,366
Nonaccrual interest not accrued
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Home equity loans [Member]
Nonaccrual loans		14,461		3,397
Ending balance, loans		20,123,838		20,544,370
Nonaccrual interest not accrued		49		66
Home equity loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		5,307
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				5,602
Ending balance, loans	[1]	21,080,304		3,196,436
Nonaccrual interest not accrued				317
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		186,394
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Legacy Loans [Member]
Current		242,532,335		207,328,184
Past due		1,689,248		578,823
Nonaccrual loans		5,136,860		1,990,539
Ending balance, loans		249,358,443	[2]	209,897,546	[2]	$ 184,732,846
Nonaccrual interest not accrued		13,341		123,326
Legacy Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		1,329,771		504,192
Legacy Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		29,379		74,631
Legacy Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		330,098
Legacy Loans [Member] | Real Estate Loans [Member]
Ending balance, loans	[2]	181,473,422		174,842,452
Legacy Loans [Member] | Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		409,451		426,354
Ending balance, loans		74,806,476				49,425,637
Nonaccrual interest not accrued		7,378		6,460
Legacy Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		1,138,070		69,618
Legacy Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		29,379		74,631
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		5,293		13,976
Ending balance, loans		9,627,329				10,919,294
Nonaccrual interest not accrued		5,914		6,982
Legacy Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due				320,971
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		330,098
Legacy Loans [Member] | Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans		4,707,655		1,546,812
Ending balance, loans		94,957,970	[2],[3]	92,665,689	[2]	91,086,852
Nonaccrual interest not accrued				109,818
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
Ending balance, loans		2,081,647	[2]	1,881,541	[2]	999,407
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				113,603
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
Ending balance, loans		34,042,543	[2]	19,518,029	[2]	16,210,542
Nonaccrual interest not accrued
Legacy Loans [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Legacy Loans [Member] | Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
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		14,461		3,397
Ending balance, loans		13,664,414	[2]	13,278,229	[2]	13,427,376
Nonaccrual interest not accrued		49		66
Legacy Loans [Member] | Home equity loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		5,307
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
Ending balance, loans		20,178,064	[1],[2]	2,258,836	[1],[2]	2,663,738
Nonaccrual interest not accrued
Legacy Loans [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		186,394
Legacy Loans [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Legacy Loans [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due
Acquired Loans [Member]
Current		117,429,115		128,769,860
Past due		510,560		21,030
Nonaccrual loans		351,181		311,396
Ending balance, loans		118,290,856		129,102,286		144,920,670
Nonaccrual interest not accrued		38,148		58,787
Acquired Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		249,207
Acquired Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		183,004
Acquired Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		78,349		21,030
Acquired Loans [Member] | Real Estate Loans [Member]
Ending balance, loans		109,260,409		118,879,208
Acquired Loans [Member] | Real Estate Loans [Member] | Residential [Member]
Nonaccrual loans		351,181		248,663
Ending balance, loans		77,663,426				91,528,556
Nonaccrual interest not accrued		38,148		35,177
Acquired Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		249,207
Acquired Loans [Member] | Real Estate Loans [Member] | Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		128,203
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				57,131
Ending balance, loans		18,423,892				22,076,549
Nonaccrual interest not accrued				23,293
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		54,801
Acquired Loans [Member] | Real Estate Loans [Member] | Investor Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		78,349		21,030
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial [Member]
Nonaccrual loans
Ending balance, loans		12,114,557		14,898,523		17,379,910
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
Acquired Loans [Member] | Real Estate Loans [Member] | Commercial construction [Member]
Nonaccrual loans
Ending balance, loans		1,058,534		1,308,652		1,797,272
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
Ending balance, loans		1,668,783		2,019,337		2,133,711
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
Ending balance, loans		6,459,424		7,266,141		8,996,210
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				5,602
Ending balance, loans		902,240	[1]	937,600	[1]	$ 1,008,462
Nonaccrual interest not accrued				317
Acquired Loans [Member] | Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
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" consumer loans as of September 30, 2017 includes $18.4 million of recreational vehicle loans purchased in August 2017.

[2] 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".

[3] "Legacy" commercial business loans at June 30, 2017 includes $15.4 million of loans purchased in June 2017.