COVID-19 (Details) - COVID-19 [Member] $ in Millions	3 Months Ended
Jun. 30, 2020 USD ($) Loan Customer
COVID-19 [Abstract]
Number of loan deferrals \| Loan	3,668
Amount of loan deferrals	$ 756.6
Number of customers with second-time loan deferrals \| Customer	50
Amount of second-time loan deferrals	$ 68.4
Paycheck Protection Program [Member]
COVID-19 [Abstract]
Number of loans authorized \| Loan	2,848
Amount of PPP loans authorized	$ 275.9
Number of loans closed \| Loan	2,782
Amount of loans closed	$ 274.1
PPP Loans Under $350 Thousand [Member]
COVID-19 [Abstract]
Number of loans authorized \| Loan	2,703
PPP Loans Between $350 Thousand and $2.0 Million [Member]
COVID-19 [Abstract]
Number of loans authorized \| Loan	132
PPP Loans Over $2.0 Million [Member]
COVID-19 [Abstract]
Number of loans authorized \| Loan	13
Commercial Loan [Member]
COVID-19 [Abstract]
Number of loan deferrals \| Loan	850
Amount of loan deferrals	$ 639.4
Number of customers with second-time loan deferrals \| Customer	30
Amount of second-time loan deferrals	$ 65.7
Residential Loan [Member]
COVID-19 [Abstract]
Number of loan deferrals \| Loan	485
Amount of loan deferrals	$ 63.3
Number of customers with second-time loan deferrals \| Customer	18
Amount of second-time loan deferrals	$ 2.2
Consumer Loan [Member]
COVID-19 [Abstract]
Number of loan deferrals \| Loan	2,264
Amount of loan deferrals	$ 44.6
Serviced Loan [Member]
COVID-19 [Abstract]
Number of loan deferrals \| Loan	69
Amount of loan deferrals	$ 9.3
Number of customers with second-time loan deferrals \| Customer	2
Amount of second-time loan deferrals	$ 0.5

The amount of second-time loan deferrals made during the period.

No definition available.

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- Definition

Amount of loans authorized under Paycheck Protection Program (PPP).

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Amount of loans closed under Payment Protection Program (PPP).

+ References

No definition available.

+ Details

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- Definition

Number of loans authorized under Paycheck Protection Program (PPP).

+ References

No definition available.

+ Details

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Namespace Prefix:	ctbi_
Data Type:	xbrli:integerItemType
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- Definition

Number of loans closed under Payment Protection Program (PPP).

+ References

No definition available.

+ Details

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- Definition

Number of loans deferred in portfolio, including but not limited to, commercial, residential, consumer and serviced loans.

+ References

No definition available.

+ Details

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Namespace Prefix:	ctbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of customers who have received loan deferrals a second time during the period.

+ References

No definition available.

+ Details

Name:	ctbi_NumberOfCustomersWithSecondTimeLoanDeferrals
Namespace Prefix:	ctbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

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 http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522

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- Details

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Data Type:	na
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- Details

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