Summary of Significant Accounting Policies - Supplemental Executive Retirement Plan (Details)	12 Months Ended
Sep. 30, 2022 item
Supplemental Executive Retirement Plan [Abstract]
Number of former executives benefited	2

In connection with the acquisition of CFSB, The Chinatown Federal Savings Bank Supplemental Executive Retirement Plan provides benefits to former executives of CFSB.

No definition available.

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