Retirement Benefits (Tables)

6 Months Ended

Mar. 31, 2024

Retirement Benefits [Abstract]

Schedule of Net Periodic (Benefit) Cost

The components of net periodic cost for our defined benefit pension plans for the three and six months ended 31 March 2024 and 2023 were as follows:

	Pension Benefits
	2024			2023
Three Months Ended 31 March	U.S.	International	Total	U.S.	International	Total
Service cost	$2.4	$2.8	$5.2	$2.8	$3.0	$5.8
Non-service cost:
Interest cost	33.7	15.0	48.7	32.5	14.9	47.4
Expected return on plan assets	(30.0)	(11.9)	(41.9)	(31.8)	(12.2)	(44.0)
Prior service cost amortization	0.3	0.3	0.6	0.3	0.1	0.4
Actuarial loss amortization	14.3	3.2	17.5	15.0	3.0	18.0
Settlements	—	0.2	0.2	0.9	0.2	1.1
Other	—	0.1	0.1	—	0.2	0.2
Net Periodic Cost	$20.7	$9.7	$30.4	$19.7	$9.2	$28.9

	Pension Benefits
	2024			2023
Six Months Ended 31 March	U.S.	International	Total	U.S.	International	Total
Service cost	$4.8	$5.6	$10.4	$5.5	$6.3	$11.8
Non-service cost:
Interest cost	67.4	29.8	97.2	65.0	29.3	94.3
Expected return on plan assets	(60.0)	(23.5)	(83.5)	(63.6)	(24.0)	(87.6)
Prior service cost amortization	0.6	0.5	1.1	0.6	0.1	0.7
Actuarial loss amortization	28.6	6.4	35.0	29.8	6.0	35.8
Settlements	—	0.2	0.2	0.9	0.2	1.1
Curtailments	—	—	—	—	(1.9)	(1.9)
Other	—	0.2	0.2	—	0.5	0.5
Net Periodic Cost	$41.4	$19.2	$60.6	$38.2	$16.5	$54.7