COVER - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 12, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	0-13888
Entity Registrant Name	CHEMUNG FINANCIAL CORP
Entity Incorporation, State or Country Code	NY
Entity Tax Identification Number	16-1237038
Entity Address, Address Line One	One Chemung Canal Plaza
Entity Address, City or Town	Elmira
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	14901
City Area Code	607
Local Phone Number	737-3711
Title of 12(b) Security	Common Stock, Par Value $0.01 Per Share
Trading Symbol	CHMG
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	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 103,726,256
Entity Common Stock, Shares Outstanding		4,661,598
Documents Incorporated by Reference	Portions of the Proxy Statement for the Annual Meeting of Shareholders to be held on June 8, 2021 are incorporated by reference into Part III, Items 10, 11, 12, 13, and 14 of this Form 10-K.
Entity Central Index Key	0000763563
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false