Loans Receivable - Schedule of Accretable Yield, or Income Expected to be Collected (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2025	Jun. 30, 2025
Schedule of Accretable Yield, or Income Expected to be Collected [Abstract]
Balance at beginning of period	$ 227	$ 260
Accretion of income	(7)	(33)
Balance at end of period	$ 220	$ 227

The aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan. This relates to loans with deteriorating of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

No definition available.

Name:	kffb_CertainLoanAcquiredInTransferAccretableYield
Namespace Prefix:	kffb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant