Allowance for Credit Losses - Loans Modified (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2025 USD ($)
Allowance for Credit Losses
Total Class of Financing Receivable	0.01%
Interest Rate Reduction
Allowance for Credit Losses
$ Amount	$ 104
Combination Term Extension and Principal Forgiveness
Allowance for Credit Losses
$ Amount	193
Combination Term Extension Interest Rate Reduction
Allowance for Credit Losses
$ Amount	$ 279
Residential | First Liens
Allowance for Credit Losses
Total Class of Financing Receivable	0.05%
Residential | First Liens | Interest Rate Reduction
Allowance for Credit Losses
$ Amount	$ 104
Residential | First Liens | Combination Term Extension Interest Rate Reduction
Allowance for Credit Losses
$ Amount	$ 136
Residential | Junior Liens
Allowance for Credit Losses
Total Class of Financing Receivable	0.08%
Residential | Junior Liens | Combination Term Extension Interest Rate Reduction
Allowance for Credit Losses
$ Amount	$ 53
Consumer | Motor Vehicle
Allowance for Credit Losses
Total Class of Financing Receivable	0.04%
Consumer | Motor Vehicle | Combination Term Extension and Principal Forgiveness
Allowance for Credit Losses
$ Amount	$ 193
Consumer | Motor Vehicle | Combination Term Extension Interest Rate Reduction
Allowance for Credit Losses
$ Amount	$ 90