Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Jan. 31, 2021	Jun. 30, 2020
Cover [Abstract]
Entity Registrant Name	COMMUNITY TRUST BANCORP INC /KY/
Entity Central Index Key	0000350852
Current Fiscal Year End Date	--12-31
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Document Transition Report	false
Entity File Number	001-31220
Entity Incorporation, State or Country Code	KY
Entity Tax Identification Number	61-0979818
Entity Address, Address Line One	346 North Mayo Trail
Entity Address, Address Line Two	P.O. Box 2947
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
Title of 12(b) Security	Common Stock
Trading Symbol	CTBI
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 552.8
Entity Common Stock, Shares Outstanding		17,826,076