SECURITIES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Proceeds from sales	$ 227,305,000
Proceeds from the sale of held to maturity securities	0	$ 0
Chemung Risk Management
Debt Securities, Available-for-sale [Line Items]
Proceeds from sales		0
Deferred Compensation Plan
Debt Securities, Available-for-sale [Line Items]
Investments, fair value	3,200,000	2,600,000
Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Investments, fair value	$ 600,000	$ 600,000