| Document and Entity Information | Sep. 30, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Sep. 30, 2020 |
| Entity Registrant Name | Community Trust Bancorp, Inc. |
| Entity Incorporation, State or Country Code | KY |
| Entity File Number | 001-31220 |
| Entity Tax Identification Number | 61-0979818 |
| Entity Address, Address Line One | P.O. Box 2947 |
| Entity Address, Address Line Two | 346 North Mayo Trail |
| Entity Address, City or Town | Pikeville |
| Entity Address, State or Province | KY |
| Entity Address, Postal Zip Code | 41502 |
| City Area Code | 606 |
| Local Phone Number | 432-1414 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000350852 |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | CTBI |
| Security Exchange Name | NASDAQ |
