Retirement Benefits (Tables)

9 Months Ended

Jun. 30, 2023

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,
	2023		2022		2023		2022
Service cost	$	9.4	$	15.4	$	30.6	$	56.1
Interest cost	35.3		34.5		114.0		99.3
Expected return on plan assets	(44.0)		(56.4)		(147.0)		(175.1)
Amortization of prior service cost	0.1		—		0.1		0.8
Amortization of net actuarial loss (gain)	0.2		10.4		(1.8)		55.0
Settlement and curtailment charges (benefit)	2.2		(0.7)		120.1		24.2
Net periodic pension benefit cost	$	3.2	$	3.2	$	116.0	$	60.3

	Other Postretirement Benefits
	Three Months Ended June 30,				Nine Months Ended June 30,
	2023		2022		2023		2022
Service cost	$	0.2	$	0.2	$	0.4	$	0.6
Interest cost	0.6		0.3		1.7		0.9
Amortization of prior service credit	—		(0.2)		—		(0.6)
Amortization of net actuarial loss	0.1		0.2		0.4		0.5
Net periodic postretirement benefit cost	$	0.9	$	0.5	$	2.5	$	1.4