PENSION, HEALTH CARE AND OTHER POSTRETIREMENT BENEFITS - Summary of the Components of Net Periodic Benefit Cost and Cumulative Other Comprehensive Loss Related to Postretirement Benefits Other than Pensions (Details) - Other Postretirement Benefits - Domestic - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Net periodic benefit credit:
Service cost	$ 0.2	$ 0.5	$ 0.6
Interest cost	6.7	6.8	7.4
Amortization of actuarial gains	(2.4)	(0.4)	0.1
Amortization of prior service credit	(14.3)	(23.9)	(23.9)
Net periodic benefit credit	(9.8)	(17.0)	(15.8)
Other changes in benefit obligation recognized in AOCI (before taxes):
Net actuarial gain arising during the year	(2.3)	(8.6)	(8.0)
Amortization of actuarial gains	2.4	0.4	(0.1)
Amortization of prior service credit	14.3	23.9	23.9
Total recognized in AOCI	14.4	15.7	15.8
Total recognized in net periodic pension (credit) cost and AOCI	$ 4.6	$ (1.3)	$ 0.0