Loans, Troubled Debt Restructurings Segregated by Class (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016 USD ($) Loan	Mar. 31, 2015 USD ($) Loan	Dec. 31, 2015 USD ($) Loan
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	25	6	34
Post-Modification Outstanding Balance	$ 10,211	$ 326	$ 11,127
Commitment to extend additional credit on loans modified	$ 2
Past due period for loan to be considered in default, minimum	90 days
Defaulted restructured loans, number of loans \| Loan	2	1
Defaulted restructured loans, recorded investment	$ 868	$ 261
Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	9,887	326	8,519
Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0	0	0
Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	$ 324	$ 0	$ 2,608
Commercial [Member] \| Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	1		3
Post-Modification Outstanding Balance	$ 1,288		$ 428
Commercial [Member] \| Construction [Member] \| Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	1,288		428
Commercial [Member] \| Construction [Member] \| Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0		0
Commercial [Member] \| Construction [Member] \| Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	$ 0		$ 0
Commercial [Member] \| Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	13	4	21
Post-Modification Outstanding Balance	$ 4,042	$ 290	$ 6,004
Defaulted restructured loans, number of loans \| Loan	1	1
Defaulted restructured loans, recorded investment	$ 510	$ 261
Commercial [Member] \| Real Estate [Member] \| Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	3,998	290	4,244
Commercial [Member] \| Real Estate [Member] \| Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0	0	0
Commercial [Member] \| Real Estate [Member] \| Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	$ 44	$ 0	$ 1,760
Commercial [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	10	2	7
Post-Modification Outstanding Balance	$ 4,601	$ 36	$ 3,847
Defaulted restructured loans, number of loans \| Loan	1	0
Defaulted restructured loans, recorded investment	$ 358	$ 0
Commercial [Member] \| Other [Member] \| Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	4,601	36	3,847
Commercial [Member] \| Other [Member] \| Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0	0	0
Commercial [Member] \| Other [Member] \| Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	$ 0	$ 0	$ 0
Residential [Member] \| Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	1		3
Post-Modification Outstanding Balance	$ 280		$ 848
Residential [Member] \| Real Estate [Member] \| Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0		0
Residential [Member] \| Real Estate [Member] \| Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0		0
Residential [Member] \| Real Estate [Member] \| Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	$ 280		$ 848

Refers to the commitments to extend additional credit on loans that are considered troubled debt restructurings.

No definition available.

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Namespace Prefix:	ctbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Refers to the minimum past due period for a loan to be considered in default, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- 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

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Namespace Prefix:	us-gaap_
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- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524

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- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953682-111524

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- Definition

Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

+ References

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