Fair Market Value of Financial Assets and Liabilities (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Impaired loan (collateral dependent) [Abstract]
Impaired loans, fair value adjustments	$ 400,000ctbi_FairValueAdjustmentOnImpairedLoans	$ 600,000ctbi_FairValueAdjustmentOnImpairedLoans
Other real estate owned [Abstract]
Other real estate /assets owned, fair value adjustment	1,700,000	2,500,000
Typical frequency of periodic reviews, minimum	12 months
Typical frequency of periodic reviews, maximum	18 months
Maximum frequency of periodic reviews	24 months
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total recognized gains (losses) Included in net income	(830,000)	206,000
Total gains (losses) for the period included in net income attributable to the change in unrealized gains or losses related to assets still held at the reporting date	(830,000)	206,000
Total gains (losses), noninterest income	(830,000)	206,000
Total gains (losses), noninterest expense	0	0
Recurring [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	188,932,000	72,623,000
State and political subdivisions	137,458,000	116,703,000
U.S. government sponsored agency mortgage-backed securities	288,907,000	367,297,000
Marketable equity securities	24,889,000	52,782,000
Mortgage servicing rights	2,968,000	3,424,000
Recurring [Member] \| Mortgage Servicing Rights [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3,424,000	2,364,000
Total recognized gains (losses) Included in net income	(467,000)	788,000
Issues	374,000	854,000
Settlements	(363,000)	(582,000)
Ending balance	2,968,000	3,424,000
Total gains (losses) for the period included in net income attributable to the change in unrealized gains or losses related to assets still held at the reporting date	(467,000)	788,000
Total gains (losses), noninterest income	(467,000)	788,000
Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	0	0
State and political subdivisions	0	0
U.S. government sponsored agency mortgage-backed securities	0	0
Marketable equity securities	24,889,000	52,782,000
Mortgage servicing rights	0	0
Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	188,932,000	72,623,000
State and political subdivisions	137,458,000	116,703,000
U.S. government sponsored agency mortgage-backed securities	288,907,000	367,297,000
Marketable equity securities	0	0
Mortgage servicing rights	0	0
Recurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	0	0
State and political subdivisions	0	0
U.S. government sponsored agency mortgage-backed securities	0	0
Marketable equity securities	0	0
Mortgage servicing rights	2,968,000	3,424,000
Nonrecurring [Member]
Assets measured-nonrecurring basis [Abstract]
Impaired loans (collateral dependent)	4,665,000	6,830,000
Other real estate /assets owned	6,472,000	11,111,000
Nonrecurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets measured-nonrecurring basis [Abstract]
Impaired loans (collateral dependent)	0	0
Other real estate /assets owned	0	0
Nonrecurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Assets measured-nonrecurring basis [Abstract]
Impaired loans (collateral dependent)	0	0
Other real estate /assets owned	0	0
Nonrecurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Assets measured-nonrecurring basis [Abstract]
Impaired loans (collateral dependent)	4,665,000	6,830,000
Other real estate /assets owned	$ 6,472,000	$ 11,111,000

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The amount at which an asset could be bought or sold in a current transaction between willing parties, that is, other than in a forced or liquidation sale.

+ References

No definition available.

+ Details

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- Definition

The amount at which an asset could be bought or sold in a current transaction between willing parties, that is, other than in a forced or liquidation sale.

+ References

No definition available.

+ Details

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- Definition

This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income (or changes in net assets) in other expense. Such unrealized (holding) gains or losses relate to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

+ References

No definition available.

+ Details

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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- Definition

+ References

No definition available.

+ Details

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- Definition

+ References

No definition available.

+ Details

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- Definition

The maximum frequency of periodic reviews for appraisals on foreclosed properties and other real estate owned generally.

+ References

No definition available.

+ Details

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- Definition

The typical maximum frequency of periodic reviews for appraisals on foreclosed properties and other real estate owned.

+ References

No definition available.

+ Details

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- Definition

The typical minimum frequency of periodic reviews for appraisals on foreclosed properties and other real estate owned.

+ References

No definition available.

+ Details

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- Definition

+ References

No definition available.

+ Details

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- Definition

This item represent fair value disclosure in U.S. government agency mortgage-backed securities, available-for-sale at fair value.

+ References

No definition available.

+ Details

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- Definition

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No definition available.

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- Definition

Fair value portion of investments accounted under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 25

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=35740979&loc=d3e32014-111567

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- Definition

Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)

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- Definition

Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

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