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

Reflects the gross carrying amount of unpaid loans secured by borrowers automobiles.

No definition available.

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

Amount before allowance of loans issued to build, improve or remodel a residential home. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreement.

No definition available.

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

Reflects the gross carrying amount of unpaid loans issued against deposits.

No definition available.

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

The amount of multi-family.

No definition available.

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

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

No definition available.

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

The amount of one-to four-family.

No definition available.

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

Reflects the gross carrying amount of unsecured unpaid loans.

No definition available.

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

Amount before allowance of revolving, open-end loan, extended under a line of credit and secured by the borrower's residential property. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreement.

No definition available.

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

Amount before allowance of loans issued to agricultural institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreement.

No definition available.

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

No definition available.

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

It represents the loans receivable of commercial non mortgage during the period.

No definition available.

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

Amount before allowance of commercial loans issued to businesses to acquire, develop, construct, improve, or refinance land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreement.

No definition available.

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

- References

No definition available.

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

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522