Loans Receivable - Narrative (Details) $ in Thousands |
6 Months Ended | ||
|---|---|---|---|
|
Mar. 31, 2026
USD ($)
portfolioSegment
loan
|
Mar. 31, 2025
loan
|
Sep. 30, 2025
USD ($)
|
|
| Receivables [Abstract] | |||
| Number of portfolio segments for loans held for investment | portfolioSegment | 2 | ||
| Accrued interest receivables for loans | $ 82,142 | $ 85,444 | |
| Loans pledged to secure borrowings from the federal home loan bank | 13,440,000 | ||
| Nonaccrual interest income recognized | 844 | ||
| Individually evaluated for credit loss, interest income | $ 3,916 | ||
| Number of loans, modified, subsequent default | loan | 1 | 0 | |