Name:	kffb_LoansReceivableTextualAbstract
Namespace Prefix:	kffb_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of bankruptcy proceedings to borrower.

No definition available.

Name:	kffb_PercentageOfBankruptcyProceedingsToBorrower
Namespace Prefix:	kffb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represent secondary mortgage loan.

No definition available.

Name:	kffb_SecondaryMortgageLoan
Namespace Prefix:	kffb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

For loans and debt securities, 1) for which at acquisition it was probable that the investor would be unable to collect all contractually required payments receivable, and 2) for which it is further probable that the investor will not be able to collect all cash flows expected at acquisition (plus any additional cash flows expected due to changes in estimate after acquisition), the allowance for credit losses recorded to reflect the impairment since acquisition.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5275-111524

Name:	us-gaap_CertainLoansAndDebtSecuritiesAcquiredInTransferAllowanceForCreditLossesDueToSubsequentImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount, after troubled debt restructuring, of modified financing receivable.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524