PENSION PLAN AND OTHER BENEFIT PLANS - Additional Information (Details) - USD ($)			12 Months Ended
	Jan. 01, 2017	Oct. 20, 2016	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Period of employment multiplier			5 years
Actuarial gain (loss), decrease due to change in mortality losses			$ 200,000
Average total life expectancy of participants (years)			10 years 2 months 12 days
Hours requirement to be eligible		1000 hours
Percentage increase (decrease) in unrecognized net loss of the projected benefit obligation			(0.16)
All other sources gain (loss) (less than)			$ 1,000
Defined Contribution Profit Sharing, Savings and Investment Plan
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer non-discretionary contribution amount	3.00%		3.00%
Contribution cost percentage	50.00%		50.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay	6.00%		6.00%
Total expense			$ 1,400,000
Chemung common stock included in defined contribution plan assets (in shares)			124,214	121,847
Defined Contribution Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Total expense			$ 600,000	$ 500,000
Balance in the plan			3,400,000	2,900,000
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation			31,000,000	30,500,000
Actuarial gain (loss), increase due to change in discount rate			$ 1,000,000
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			$ 1,000,000
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			$ 2,100,000
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%
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			$ 16,000
Contribution cost percentage			50.00%
Decrease in accumulated benefit obligation due to change in discount rate			$ 1,000
Increase in accumulated benefit obligation due to discount rate, claims and date experience			$ 6,000
Average future working lifetime of active participants			6 years
Estimated employer contributions in next fiscal year			$ 12,000
Executive Supplemental Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation			900,000	$ 900,000
Actuarial gain (loss), increase due to change in discount rate			20,000
Actuarial gain (loss), decrease due to change in mortality losses			$ 8,000
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)			10 years 2 months 1 day
Decrease in accumulated benefit obligation due to discount rate, health care trend rates			$ 4,000
Percentage increase (decrease) in unrecognized net loss of the projected benefit obligation			0.032
Estimated employer contributions in next fiscal year			$ 110,000
Actuarial gain (loss), increase (decrease) due to change in mortality longevity			25,000
Defined benefit plan, increase in total unrecognized net loss			30,000
All other sources gain (loss) (less than)			$ 0