Loans Receivable And Allowance For Loan Losses: Past Due Status of Loans (Details) - USD ($) $ in Thousands		Mar. 31, 2021		Sep. 30, 2020
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		$ 3,928		$ 3,748
Loans receivable, Non-Accrual	[1]	2,305		2,905
Loans receivable, Current		1,047,188		1,029,977
Loans receivable		1,051,116		1,033,725
Mortgage loans, one-to-four family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		415		727
Loans receivable, Non-Accrual	[1]	415		659
Loans receivable, Current		116,769		117,853
Loans receivable		117,184		118,580
Mortgage loans, multi-family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Loans receivable, Non-Accrual	[1]	0		0
Loans receivable, Current		92,435		85,053
Loans receivable		92,435		85,053
Mortgage loans, commercial
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		1,157		1,377
Loans receivable, Non-Accrual	[1]	643		858
Loans receivable, Current		460,809		452,197
Loans receivable		461,966		453,574
Mortgage loans, construction - custom and owner/builder
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		808		0
Loans receivable, Non-Accrual	[1]	0		0
Loans receivable, Current		62,165		75,332
Loans receivable		62,973		75,332
Mortgage loans, construction - speculative one-to-four family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Loans receivable, Non-Accrual	[1]	0		0
Loans receivable, Current		7,336		7,108
Loans receivable		7,336		7,108
Mortgage loans, construction – commercial
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Loans receivable, Non-Accrual	[1]	0		0
Loans receivable, Current		34,217		20,927
Loans receivable		34,217		20,927
Mortgage loans, construction - Multi-family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Loans receivable, Non-Accrual	[1]	0		0
Loans receivable, Current		15,739		10,832
Loans receivable		15,739		10,832
Mortgage loans, construction - Land development
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		38
Loans receivable, Non-Accrual	[1]	0		0
Loans receivable, Current		623		4,701
Loans receivable		623		4,739
Mortgage loans, land
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		390		538
Loans receivable, Non-Accrual	[1]	173		394
Loans receivable, Current		18,651		25,033
Loans receivable		19,041		25,571
Consumer loans, home equity and second mortgage
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		612		577
Loans receivable, Non-Accrual	[1]	539		555
Loans receivable, Current		31,414		31,500
Loans receivable		32,026		32,077
Consumer loans, other
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		19		12
Loans receivable, Non-Accrual	[1]	8		9
Loans receivable, Current		2,737		3,560
Loans receivable		2,756		3,572
Commercial business loans
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		527		479
Loans receivable, Non-Accrual		527	[1]	430
Loans receivable, Current		66,118		69,061
Loans receivable		66,645		69,540
SBA PPP Loans
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Loans receivable, Non-Accrual		0		0	[1]
Loans receivable, Current		138,175		126,820
Loans receivable		138,175		126,820
30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		1,550		52
30 to 59 Days Past Due | Mortgage loans, one-to-four family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
30 to 59 Days Past Due | Mortgage loans, multi-family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
30 to 59 Days Past Due | Mortgage loans, commercial
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		514		0
30 to 59 Days Past Due | Mortgage loans, construction - custom and owner/builder
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		808		0
30 to 59 Days Past Due | Mortgage loans, construction - speculative one-to-four family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
30 to 59 Days Past Due | Mortgage loans, construction – commercial
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
30 to 59 Days Past Due | Mortgage loans, construction - Multi-family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
30 to 59 Days Past Due | Mortgage loans, construction - Land development
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
30 to 59 Days Past Due | Mortgage loans, land
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		217		0
30 to 59 Days Past Due | Consumer loans, home equity and second mortgage
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
30 to 59 Days Past Due | Consumer loans, other
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		11		3
30 to 59 Days Past Due | Commercial business loans
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		49
30 to 59 Days Past Due | SBA PPP Loans
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		73		791
60 to 89 Days Past Due | Mortgage loans, one-to-four family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		68
60 to 89 Days Past Due | Mortgage loans, multi-family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
60 to 89 Days Past Due | Mortgage loans, commercial
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		519
60 to 89 Days Past Due | Mortgage loans, construction - custom and owner/builder
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
60 to 89 Days Past Due | Mortgage loans, construction - speculative one-to-four family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
60 to 89 Days Past Due | Mortgage loans, construction – commercial
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
60 to 89 Days Past Due | Mortgage loans, construction - Multi-family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
60 to 89 Days Past Due | Mortgage loans, construction - Land development
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		38
60 to 89 Days Past Due | Mortgage loans, land
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		144
60 to 89 Days Past Due | Consumer loans, home equity and second mortgage
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		73		22
60 to 89 Days Past Due | Consumer loans, other
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
60 to 89 Days Past Due | Commercial business loans
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0
60 to 89 Days Past Due | SBA PPP Loans
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Mortgage loans, one-to-four family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Mortgage loans, multi-family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Mortgage loans, commercial
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Mortgage loans, construction - custom and owner/builder
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Mortgage loans, construction - speculative one-to-four family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Mortgage loans, construction – commercial
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Mortgage loans, construction - Multi-family
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Mortgage loans, construction - Land development
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Mortgage loans, land
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Consumer loans, home equity and second mortgage
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Consumer loans, other
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0		0
Past Due 90 Days or More and Still Accruing | Commercial business loans
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		0
Past Due 90 Days or More and Still Accruing | SBA PPP Loans
Financing Receivable, Past Due [Line Items]
Loans receivable, Total Past Due		$ 0		$ 0

[1] Includes non-accrual loans past due 90 days or more and other loans classified as non-accrual.