Allowance for Credit Losses - Loans Modified (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2026 USD ($)
Allowance for Credit Losses
Total Class of Financing Receivable	0.01%
Principal Forgiveness
Allowance for Credit Losses
$ Amount	$ 22
Term Extension
Allowance for Credit Losses
$ Amount	387
Combination Term Extension and Principal Forgiveness
Allowance for Credit Losses
$ Amount	87
Combination Term Extension Interest Rate Reduction
Allowance for Credit Losses
$ Amount	$ 119
Residential \| First Liens
Allowance for Credit Losses
Total Class of Financing Receivable	0.06%
Residential \| First Liens \| Term Extension
Allowance for Credit Losses
$ Amount	$ 302
Residential \| First Liens \| Combination Term Extension Interest Rate Reduction
Allowance for Credit Losses
$ Amount	$ 46
Residential \| Junior Liens
Allowance for Credit Losses
Total Class of Financing Receivable	0.02%
Residential \| Junior Liens \| Term Extension
Allowance for Credit Losses
$ Amount	$ 14
Residential \| All Other Residential
Allowance for Credit Losses
Total Class of Financing Receivable	0.21%
Residential \| All Other Residential \| Combination Term Extension Interest Rate Reduction
Allowance for Credit Losses
$ Amount	$ 73
Consumer \| Motor Vehicle
Allowance for Credit Losses
Total Class of Financing Receivable	0.03%
Consumer \| Motor Vehicle \| Principal Forgiveness
Allowance for Credit Losses
$ Amount	$ 22
Consumer \| Motor Vehicle \| Term Extension
Allowance for Credit Losses
$ Amount	71
Consumer \| Motor Vehicle \| Combination Term Extension and Principal Forgiveness
Allowance for Credit Losses
$ Amount	$ 87