Fair Market Value of Financial Assets and Liabilities (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Other real estate owned [Abstract]
Maximum frequency of periodic reviews of real estate owned in general	24 months
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total recognized losses included in net income	$ (255,000)		$ (229,000)
Total 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	(255,000)		(229,000)
Total gains (losses), noninterest income	(255,000)		(229,000)
Total gains (losses), noninterest expense	0		0
Minimum [Member]
Other real estate owned [Abstract]
Frequency of periodic reviews	12 months
Maximum [Member]
Other real estate owned [Abstract]
Frequency of periodic reviews	18 months
Recurring [Member] \| Mortgage Servicing Rights [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	2,968,000		3,424,000
Total recognized losses included in net income	(161,000)		(126,000)
Issues	84,000		63,000
Settlements	(94,000)		(103,000)
Ending balance	2,797,000		3,258,000
Total 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	(161,000)		(126,000)
Total gains (losses), noninterest income	(161,000)		(126,000)
Recurring [Member] \| Fair Value [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	186,714,000	188,932,000
State and political subdivisions	136,313,000	137,458,000
U.S. government sponsored agency mortgage-backed securities	278,188,000	288,907,000
CRA investment funds	25,120,000	24,889,000
Mortgage servicing rights	2,797,000	2,968,000
Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	498,000	492,000
State and political subdivisions	0	0
U.S. government sponsored agency mortgage-backed securities	0	0
CRA investment funds	25,120,000	24,889,000
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	186,216,000	188,440,000
State and political subdivisions	136,313,000	137,458,000
U.S. government sponsored agency mortgage-backed securities	278,188,000	288,907,000
CRA investment funds	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
CRA investment funds	0	0
Mortgage servicing rights	2,797,000	2,968,000
Nonrecurring [Member]
Impaired loan (collateral dependent) [Abstract]
Impaired loans, fair value adjustments	500,000	300,000	200,000
Other real estate owned [Abstract]
Other real estate /assets owned, fair value adjustment	50,000	1,500,000	800,000
Nonrecurring [Member] \| Fair Value [Member]
Assets measured-nonrecurring basis [Abstract]
Impaired loans (collateral dependent)	2,760,000	4,665,000
Other real estate /assets owned	265,000	6,472,000
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)	2,760,000	4,665,000
Other real estate /assets owned	$ 265,000	$ 6,472,000

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Fair value portion of CRA investment funds.

+ References

No definition available.

+ Details

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Period Type:	instant

- 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

Name:	ctbi_FairValueAdjustmentOnImpairedLoans
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Balance Type:	debit
Period Type:	duration

- 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

Frequency of periodic reviews is based upon consideration of the specific properties and the known or perceived market fluctuations in a particular market and is typically between certain range of months.

+ References

No definition available.

+ Details

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- 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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Namespace Prefix:	ctbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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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Namespace Prefix:	ctbi_
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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

+ References

No definition available.

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- Details

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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)

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

+ Details

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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)

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

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