BENEFIT PLANS: (Tables)

6 Months Ended

Jun. 30, 2025

Defined contribution plan and post-retirement defined benefit plans

Components of net periodic benefit costs

Schedule of the components of net periodic benefit costs

The components of net periodic benefit costs for the six-month periods ended June 30, 2025 and 2024 are as follows (in millions):

	Six months ended
	June 30,
(in millions)	2025		2024
Service cost	$	1.2	$	1.3
Interest cost		1.9		2.0
Expected return on plan assets		(3.6)		(3.2)
Amortization of prior service cost / (credit)		0.1		0.2
Amortization of net loss/(gain)		0.1		—
Net periodic (benefit) cost	$	(0.3)	$	0.3

Post-retirement health care plans

Components of net periodic benefit costs

Schedule of the components of net periodic benefit costs

The components of net periodic benefit cost for the six-month periods ended June 30, 2025 and 2024 are as follows (in millions):

	Six months ended June 30,
(in millions)	2025		2024
Interest cost	$	1.0	$	1.1
Amortization of net loss (gain)		—		—
Amortization of prior service cost/ (credit)		—		—
Net periodic benefit cost	$	1.0	$	1.1