Retirement Benefits (Tables)

6 Months Ended

Mar. 31, 2020

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,
	2020			2019			2020			2019
Service cost	$	22.8		$	19.5		$	45.6		$	39.1
Interest cost	34.1			39.6			68.3			79.2
Expected return on plan assets	(61.2		)	(61.2		)	(122.4		)	(122.4		)
Amortization:
Prior service cost	0.3			0.3			0.5			0.6
Net actuarial loss	36.8			19.5			73.6			39.0
Settlements	(0.7		)	(0.2		)	(1.5		)	(0.4		)
Net periodic benefit cost	$	32.1		$	17.5		$	64.1		$	35.1

	Other Postretirement Benefits
	Three Months Ended March 31,						Six Months Ended March 31,
	2020			2019			2020			2019
Service cost	$	0.2		$	0.3		$	0.5		$	0.5
Interest cost	0.4			0.5			0.8			1.1
Amortization:
Prior service credit	(1.3		)	(1.3		)	(2.7		)	(2.7		)
Net actuarial loss	0.3			0.2			0.7			0.4
Net periodic benefit credit	$	(0.4	)	$	(0.3	)	$	(0.7	)	$	(0.7	)