Retirement Benefits (Tables)

6 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

The components of net periodic benefit cost are (in millions):

	Pension Benefits
	Three Months Ended March 31,				Six Months Ended March 31,
	2021		2020		2021		2020
Service cost	$	22.9	$	22.8	$	45.6	$	45.6
Interest cost	31.5		34.1		62.8		68.3
Expected return on plan assets	(60.7)		(61.2)		(121.1)		(122.4)
Amortization:
Prior service cost	0.3		0.3		0.7		0.5
Net actuarial loss	36.8		36.8		73.5		73.6
Settlements	(0.2)		(0.7)		(0.4)		(1.5)
Net periodic benefit cost	$	30.6	$	32.1	$	61.1	$	64.1

	Other Postretirement Benefits
	Three Months Ended March 31,				Six Months Ended March 31,
	2021		2020		2021		2020
Service cost	$	0.2	$	0.2	$	0.5	$	0.5
Interest cost	0.3		0.4		0.6		0.8
Amortization:
Prior service credit	(1.3)		(1.3)		(2.7)		(2.7)
Net actuarial loss	0.3		0.3		0.6		0.7
Net periodic benefit credit	$	(0.5)	$	(0.4)	$	(1.0)	$	(0.7)