Retirement Plans (Tables)

3 Months Ended

Dec. 31, 2023

Retirement Plans [Abstract]

Summary of Components of Net Pension Cost and Summary of Components of Postretirement Benefit Cost

Pension and Postretirement Cost

The following table presents a summary of the components of net pension cost (in millions):

	Three Months Ended
	December 31,
	2023			2022
Service cost	$	6.6		$	7.5
Interest cost		65.5			63.7
Expected return on plan assets		(76.0	)		(75.8	)
Amortization of net actuarial loss		8.1			14.5
Amortization of prior service cost		1.7			2.1
Company defined benefit plan cost		5.9			12.0
Multiemployer and other plans		0.4			0.3
Net pension cost	$	6.3		$	12.3

The following table presents a summary of the components of the net postretirement cost (in millions):

	Three Months Ended
	December 31,
	2023			2022
Service cost	$	0.2		$	0.2
Interest cost		1.9			1.8
Amortization of net actuarial gain		(1.3	)		(1.1	)
Amortization of prior service credit		(0.1	)		(0.2	)
Net postretirement cost	$	0.7		$	0.7