Retirement Benefits (Tables)

9 Months Ended

Jun. 30, 2024

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

The components of net periodic pension and postretirement benefit cost were (in millions):

	Pension Benefits
	Three Months Ended June 30,				Nine Months Ended June 30,
	2024		2023		2024		2023
Service cost	$	9.3	$	9.4	$	27.8	$	30.6
Interest cost	36.6		35.3		109.9		114.0
Expected return on plan assets	(42.2)		(44.0)		(126.9)		(147.0)
Amortization of prior service cost	—		0.1		—		0.1
Amortization of net actuarial (gain) loss	(0.3)		0.2		(0.8)		(1.8)
Settlement charge	—		2.2		—		120.1
Net periodic pension benefit cost	$	3.4	$	3.2	$	10.0	$	116.0

	Other Postretirement Benefits
	Three Months Ended June 30,				Nine Months Ended June 30,
	2024		2023		2024		2023
Service cost	$	0.1	$	0.2	$	0.4	$	0.4
Interest cost	0.6		0.6		1.9		1.7
Amortization of net actuarial loss	0.4		0.1		1.2		0.4
Net periodic postretirement benefit cost	$	1.1	$	0.9	$	3.5	$	2.5