Loans Receivable and Allowance for Credit Losses (Gross Charge-offs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	$ 96
Year Two	10
Year Three	15
Year Four	0
Year Five	0
Prior Years	39
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	160	$ 115	$ 70
One- to Four-Family Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0
Year Two	0
Year Three	0
Year Four	0
Year Five	0
Prior Years	0
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	0	0	9
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0
Year Two	0
Year Three	0
Year Four	0
Year Five	0
Prior Years	0
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	0	0	9
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0
Year Two	0
Year Three	0
Year Four	0
Year Five	0
Prior Years	0
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	0	0	0
One- to Four-Family Segment [Member] | Bulk Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0
Year Two	0
Year Three	0
Year Four	0
Year Five	0
Prior Years	0
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	0	0	0
Commercial Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	50
Year Two	0
Year Three	0
Year Four	0
Year Five	0
Prior Years	30
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	80	75	40
Commercial Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	50
Year Two	0
Year Three	0
Year Four	0
Year Five	0
Prior Years	30
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	80
Commercial Segment [Member] | Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0
Year Two	0
Year Three	0
Year Four	0
Year Five	0
Prior Years	0
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	0
Consumer Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	46
Year Two	10
Year Three	15
Year Four	0
Year Five	0
Prior Years	9
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	80	$ 40	$ 21
Consumer Segment [Member] | Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	46
Year Two	1
Year Three	0
Year Four	0
Year Five	0
Prior Years	0
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	47
Consumer Segment [Member] | Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Year One	0
Year Two	9
Year Three	15
Year Four	0
Year Five	0
Prior Years	9
Revolving Line of Credit	0
Revolving Line of Credit Converted to Term Loan	0
Total Charge-offs	$ 33