STOCK COMPENSATION - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025	Dec. 31, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested stock options granted	$ 0
Shares granted (up to) (in shares)	0	0
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense restricted stock awards	$ 791,000	$ 455,000
Unrecognized compensation cost related to nonvested restricted stock	7,400,000		$ 3,600,000
Fair value of shares vesting during period	2,700,000	1,500,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit from share-based compensation	$ 166,000	$ 96,000
Granted (in shares)	170,302
Performance Based Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Granted (in shares)	48,848		55,575	44,988
Awards distributed (in shares)	15,294
Fair value of awards distributed	$ 424,000
Key Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting per year	100.00%
Award vesting period	1 year
CNB Financial Corporation 2025 Omnibus Incentive Plan (the “2025 Stock Incentive Plan”)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (shares)	782,246
CNB Financial Corporation 2025 Omnibus Incentive Plan (the “2025 Stock Incentive Plan”) | Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting per year	33.00%
CNB Financial Corporation 2025 Omnibus Incentive Plan (the “2025 Stock Incentive Plan”) | Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting per year	25.00%