EMPLOYEE BENEFIT PLANS - Discount rate and assumptions (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Supplemental Benefit Plan
Weighted-average assumptions used to determine nonunion benefit obligations
Discount rate (as a percent)	4.80%	4.30%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)	4.30%	4.60%	1.80%
Postretirement Health Benefit Plan
Weighted-average assumptions used to determine nonunion benefit obligations
Discount rate (as a percent)	5.50%	4.80%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)	4.80%	5.00%	2.70%