Retirement Plans

6 Months Ended

Jun. 30, 2024

Retirement Benefits [Abstract]

Retirement Plans

(10) Retirement Plans

The components of the net periodic benefit cost (credit) for our plans were as follows:

	Defined Benefit Pension Plan
	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2024			2023			2024			2023
Service cost	$	4.0		$	3.9		$	8.1		$	7.7
Interest cost		4.8			5.3			9.6			10.5
Expected return on assets		(4.6	)		(4.8	)		(9.3	)		(9.4	)
Curtailments		(1.3	)		—			(1.3	)		—
Net gain		(0.4	)		(0.8	)		(0.8	)		(1.7	)
Prior service cost		0.1			0.1			0.3			0.3
Total benefit cost	$	2.6		$	3.7		$	6.6		$	7.4
	Retiree Health Care Plan
	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2024			2023			2024			2023
Interest cost	$	0.1		$	0.2		$	0.2		$	0.3
Prior service credit		(0.2	)		—			(0.4	)		—
Net gain		—			(0.2	)		—			(0.4	)
Total benefit credit	$	(0.1	)	$	—		$	(0.2	)	$	(0.1	)

During the three and six months ended June 30, 2024, contributions made to our pension plans were $4.3 and $9.5, respectively, and contributions made to our retiree health care plan were $0.2 and $0.5, respectively. During 2024, we expect to make total contributions of approximately $19.0 to our pension plans and to fund our retiree health care payments as incurred.