LOANS - NONACCRUAL, LOANS PAST DUE OVER 90 DAYS STILL ACCRUING AND TDR (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Loans
Nonaccrual	$ 1,068	$ 1,193
Loans Past Due Over 90 Days Still Accruing	$ 608	231
Percentage of nonaccrual loans secured by real estate	77.10%
Maximum period past due for loans to be considered as impaired	90 days
Commercial
Loans
Nonaccrual	$ 214
Loans Past Due Over 90 Days Still Accruing	23	32
Real estate construction
Loans
Loans Past Due Over 90 Days Still Accruing	374
1-4 family residential
Loans
Nonaccrual	508	1,086
Loans Past Due Over 90 Days Still Accruing	129	184
Non-farm & non-residential
Loans
Nonaccrual	225
Loans Past Due Over 90 Days Still Accruing	59
Agricultural
Loans
Nonaccrual	91	96
Consumer
Loans
Nonaccrual	30	11
Loans Past Due Over 90 Days Still Accruing	$ 23	$ 15

Represents the maximum period past due for loans to be considered as impaired.

No definition available.

Name:	ktyb_FinancingReceivableMaximumPeriodPastDueForLoansToBeConsideredImpaired
Namespace Prefix:	ktyb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of nonaccrual investment in financing receivables that are secured by real estate.

+ References

No definition available.

+ Details

Name:	ktyb_FinancingReceivablePercentageOfNonaccrualInvestmentSecuredByRealEstate
Namespace Prefix:	ktyb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ktyb_RealEstateConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ktyb_OneToFourFamilyResidentialMortgageLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ktyb_NonFarmAndNonResidentialMortgageLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=ktyb_AgriculturalLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: