PENSION PLAN AND OTHER BENEFIT PLANS - Additional Information (Details) - USD ($) $ in Thousands				12 Months Ended
	Jan. 01, 2023	Jan. 01, 2021	Oct. 20, 2016	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Actuarial gain (loss), increase (decrease) due to change in mortality losses				$ 200
Hours requirement to be eligible			1000 hours
Percentage decrease in unrecognized net loss of the projected benefit obligation				0.46
Defined Contribution Profit Sharing, Savings and Investment Plan
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer non-discretionary contribution amount				3.00%
Contribution cost percentage				50.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay				6.00%
Total expense				$ 1,400	$ 1,300
Chemung common stock included in defined contribution plan assets (in shares)				121,847	118,081
Defined Contribution Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Total expense				$ 500	$ 400
Balance in the plan				2,900	2,400
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation				30,500	40,400
Actuarial gain (loss), increase (decrease) due to change in discount rate				$ (9,200)
Percentage of combined loss of expected year end obligations (less than)				0.01
Other comprehensive income, defined benefit plans, decrease in net unamortized gain loss arising during period net of tax				$ 200
Other comprehensive income, defined benefit plans, increase (decrease) in net unamortized gain loss arising during period net of tax, due to variance of actual and expected return on plan assets				$ 9,000
Total unrecognized net loss increased percentage of obligation amortization threshold				10.00%
Total unrecognized net loss increased (decreased) percentage of plan assets threshold				10.00%
Average total life expectancy of participants (years)		22 years 6 months 18 days
Pension Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Evaluation period of expected long-term return on plan assets				3 years
Pension Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Evaluation period of expected long-term return on plan assets				5 years
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Other comprehensive income, defined benefit plans, decrease in net unamortized gain loss arising during period net of tax				$ 90
Contribution cost percentage				50.00%
Decrease in accumulated benefit obligation due to change in discount rate				$ 12
Decrease in accumulated benefit obligation due to discount rate, claims and date experience				64
Average future working lifetime of active participants		7 years
Estimated employer contributions in next fiscal year				27
Executive Supplemental Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation				900	$ 1,200
Actuarial gain (loss), increase (decrease) due to change in discount rate				(182)
Actuarial gain (loss), increase (decrease) due to change in mortality losses				7
Actuarial gain (loss), increase (decrease) due to change in mortality longevity				$ 27
Total unrecognized net loss increased percentage of obligation amortization threshold				10.00%
Total unrecognized net loss increased (decreased) percentage of plan assets threshold				10.00%
Increase in accumulated benefit obligation due to discount rate, health care trend rates				$ 4
Percentage decrease in unrecognized net loss of the projected benefit obligation				0.143
Estimated employer contributions in next fiscal year				$ 110
Defined benefit plan, decrease in total unrecognized net loss				$ 167
Executive Supplemental Pension Plan | Subsequent Event
Defined Benefit Plan Disclosure [Line Items]
Average total life expectancy of participants (years)	10 years 10 months 9 days