Cover - USD ($)	12 Months Ended
	Dec. 31, 2021	Mar. 01, 2022	Jun. 30, 2021
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-39472
Entity Registrant Name	CNB FINANCIAL CORP/PA
Entity Incorporation, State or Country Code	PA
Entity Tax Identification Number	25-1450605
Entity Address, Address Line One	1 South Second Street
Entity Address, Address Line Two	P.O. Box 42
Entity Address, City or Town	Clearfield
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	16830
City Area Code	814
Local Phone Number	765-9621
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 362,508,707
Entity Common Stock, Shares Outstanding (in shares)		16,910,921
Documents Incorporated by Reference	Portions of the definitive Proxy Statement for the 2021 Annual Meeting of Stockholders to be held on April 19, 2022 are incorporated by reference into Part III of this report.
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Central Index Key	0000736772
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	CCNE
Security Exchange Name	NASDAQ
Series A Preferred Stock
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares (each representing a 1/40th interest in a share of 7.125% Series A Non-Cumulative, perpetual preferred stock)
Trading Symbol	CCNEP
Security Exchange Name	NASDAQ