Loans and Allowance for Credit Losses on Loans - Loan Balances by Internal Credit Quality Indicator (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Jun. 30, 2025
Commercial Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	$ 11,546		$ 11,917
Fiscal year before latest fiscal year	11,110		11,031
Two years before latest fiscal year	10,175		8,157
Three years before latest fiscal year	7,760		10,913
Four years before latest fiscal year	10,642		12,512
Prior	26,950		15,767
Revolving loans amortized cost basis	47,772		46,221
Revolving loans converted to term	24		251
Total	125,979		116,769
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		0
Three years before latest fiscal year	0		0
Four years before latest fiscal year	0		0
Prior	0		38
Revolving loans amortized cost basis	0		28
Revolving loans converted to term	0		0
Current period gross charge-offs	0	$ 6	66
Residential Real Estate [Member] | Residential Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	8,357		42,672
Fiscal year before latest fiscal year	44,125		55,665
Two years before latest fiscal year	54,851		58,277
Three years before latest fiscal year	55,652		85,209
Four years before latest fiscal year	82,966		71,560
Prior	170,512		104,336
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total	416,463		417,719
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		0
Three years before latest fiscal year	0		0
Four years before latest fiscal year	0		44
Prior	0		0
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Current period gross charge-offs	0	44	44
Real Estate Mortgage [Member] | Commercial Real Estate Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	33,836		192,619
Fiscal year before latest fiscal year	205,167		121,362
Two years before latest fiscal year	125,859		187,886
Three years before latest fiscal year	183,507		229,616
Four years before latest fiscal year	227,245		117,152
Prior	307,540		196,714
Revolving loans amortized cost basis	3,366		3,913
Revolving loans converted to term	328		5,242
Total	1,086,848		1,054,504
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		0
Three years before latest fiscal year	0		0
Four years before latest fiscal year	0		0
Prior	0		5
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Current period gross charge-offs	0	5	5
Home Equity [Member] | Consumer Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	607		2,753
Fiscal year before latest fiscal year	2,687		4,761
Two years before latest fiscal year	4,435		2,437
Three years before latest fiscal year	2,254		229
Four years before latest fiscal year	217		315
Prior	1,132		791
Revolving loans amortized cost basis	25,766		22,667
Revolving loans converted to term	123		150
Total	37,221		34,103
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		0
Three years before latest fiscal year	0		0
Four years before latest fiscal year	0		0
Prior	0		0
Revolving loans amortized cost basis	0		13
Revolving loans converted to term	0		0
Current period gross charge-offs	0	13	13
Consumer Installment [Member] | Consumer Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	881		1,633
Fiscal year before latest fiscal year	1,149		1,371
Two years before latest fiscal year	1,185		689
Three years before latest fiscal year	605		346
Four years before latest fiscal year	273		149
Prior	172		51
Revolving loans amortized cost basis	71		72
Revolving loans converted to term	0		0
Total	4,336		4,311
Current fiscal year	86		335
Fiscal year before latest fiscal year	8		40
Two years before latest fiscal year	0		0
Three years before latest fiscal year	0		10
Four years before latest fiscal year	0		1
Prior	0		0
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Current period gross charge-offs	94	$ 77	386
Performing [Member] | Residential Real Estate [Member] | Residential Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	8,357		42,672
Fiscal year before latest fiscal year	44,125		55,665
Two years before latest fiscal year	54,851		58,277
Three years before latest fiscal year	55,652		85,153
Four years before latest fiscal year	82,911		71,560
Prior	167,937		102,127
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total	413,833		415,454
Performing [Member] | Home Equity [Member] | Consumer Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	607		2,753
Fiscal year before latest fiscal year	2,687		4,761
Two years before latest fiscal year	4,435		2,437
Three years before latest fiscal year	2,254		229
Four years before latest fiscal year	217		315
Prior	1,120		791
Revolving loans amortized cost basis	25,557		22,637
Revolving loans converted to term	123		150
Total	37,000		34,073
Performing [Member] | Consumer Installment [Member] | Consumer Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	881		1,631
Fiscal year before latest fiscal year	1,149		1,371
Two years before latest fiscal year	1,185		689
Three years before latest fiscal year	605		346
Four years before latest fiscal year	273		149
Prior	172		51
Revolving loans amortized cost basis	71		72
Revolving loans converted to term	0		0
Total	4,336		4,309
Non-performing [Member] | Residential Real Estate [Member] | Residential Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		0
Three years before latest fiscal year	0		56
Four years before latest fiscal year	55		0
Prior	2,575		2,209
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total	2,630		2,265
Non-performing [Member] | Home Equity [Member] | Consumer Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		0
Three years before latest fiscal year	0		0
Four years before latest fiscal year	0		0
Prior	12		0
Revolving loans amortized cost basis	209		30
Revolving loans converted to term	0		0
Total	221		30
Non-performing [Member] | Consumer Installment [Member] | Consumer Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	0		2
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		0
Three years before latest fiscal year	0		0
Four years before latest fiscal year	0		0
Prior	0		0
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total	0		2
Pass [Member] | Commercial Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	11,546		11,917
Fiscal year before latest fiscal year	11,110		11,031
Two years before latest fiscal year	10,175		8,157
Three years before latest fiscal year	7,749		4,584
Four years before latest fiscal year	4,355		12,482
Prior	26,110		15,106
Revolving loans amortized cost basis	47,620		45,905
Revolving loans converted to term	0		68
Total	118,665		109,250
Pass [Member] | Real Estate Mortgage [Member] | Commercial Real Estate Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	33,836		192,619
Fiscal year before latest fiscal year	205,167		120,883
Two years before latest fiscal year	125,380		177,469
Three years before latest fiscal year	173,171		228,960
Four years before latest fiscal year	226,434		116,680
Prior	289,038		177,025
Revolving loans amortized cost basis	3,366		3,913
Revolving loans converted to term	254		5,032
Total	1,056,646		1,022,581
Special Mention [Member] | Commercial Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		0
Three years before latest fiscal year	0		50
Four years before latest fiscal year	40		0
Prior	293		93
Revolving loans amortized cost basis	148		238
Revolving loans converted to term	0		183
Total	481		564
Special Mention [Member] | Real Estate Mortgage [Member] | Commercial Real Estate Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		479
Two years before latest fiscal year	479		1,339
Three years before latest fiscal year	1,327		656
Four years before latest fiscal year	651		263
Prior	3,540		4,747
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	0		0
Total	5,997		7,484
Substandard [Member] | Commercial Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		0
Three years before latest fiscal year	11		6,279
Four years before latest fiscal year	6,247		30
Prior	547		568
Revolving loans amortized cost basis	4		78
Revolving loans converted to term	24		0
Total	6,833		6,955
Substandard [Member] | Real Estate Mortgage [Member] | Commercial Real Estate Portfolio [Member]
Loans and Allowance for Credit Losses on Loans [Abstract]
Current fiscal year	0		0
Fiscal year before latest fiscal year	0		0
Two years before latest fiscal year	0		9,078
Three years before latest fiscal year	9,009		0
Four years before latest fiscal year	160		209
Prior	14,962		14,942
Revolving loans amortized cost basis	0		0
Revolving loans converted to term	74		210
Total	$ 24,205		$ 24,439