Investment Securities: Other than Temporary Impairment, Credit Losses Recognized in Earnings (Details) - USD ($) $ in Thousands |
9 Months Ended | |
|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Debt Securities, Held-to-Maturity, Allowance for Credit Loss [Roll Forward] | ||
| Beginning balance of credit loss | $ 788 | $ 803 |
| Net realized loss previously recorded as credit losses | (3) | (3) |
| Recovery of prior credit loss | (19) | (6) |
| Ending balance of credit loss | $ 766 | $ 794 |