Pension and Postretirement Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Net Pension and Postretirement Cost

Net periodic pension and postretirement benefit cost for the Company’s defined pension and postretirement benefit plans for the three and nine months ended September 30, 2023 and 2022 are set forth below (in millions):

	Three Months Ended September 30,				Nine Months Ended September 30,
Pension benefits	2023		2022		2023		2022
Service cost	$	2.4	$	3.2	$	7.2	$	9.8
Interest cost	7.5		3.6		22.0		11.4
Expected return on plan assets	(7.5)		(4.1)		(22.1)		(13.1)
Amortization of net actuarial losses	2.2		2.0		6.4		6.4
Amortization of prior service cost	0.3		—		1.0		0.1
Net periodic pension cost	$	4.9	$	4.7	$	14.5	$	14.6

	Three Months Ended September 30,				Nine Months Ended September 30,
Postretirement benefits	2023		2022		2023		2022
Service cost	$	—	$	—	$	—	$	0.1
Interest cost	0.4		0.2		1.0		0.7
Amortization of prior service cost	—		—		0.1		0.1
Net periodic postretirement benefit cost	$	0.4	$	0.2	$	1.1	$	0.9