Retirement Benefits (Tables)

6 Months Ended

Mar. 31, 2017

Compensation and Retirement Disclosure [Abstract]

Schedule of Net Benefit Costs

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

	Pension Benefits
	Three Months Ended March 31,						Six Months Ended March 31,
	2017			2016			2017			2016
Service cost	$	24.2		$	21.8		$	48.3		$	43.9
Interest cost	37.8			42.2			75.6			84.7
Expected return on plan assets	(56.2		)	(54.4		)	(112.4		)	(109.1		)
Amortization:
Prior service credit	(1.1		)	(0.7		)	(1.9		)	(1.4		)
Net actuarial loss	38.2			31.1			76.2			62.2
Settlements	—			—			0.2			—
Net periodic benefit cost	$	42.9		$	40.0		$	86.0		$	80.3

	Other Postretirement Benefits
	Three Months Ended March 31,						Six Months Ended March 31,
	2017			2016			2017			2016
Service cost	$	0.4		$	0.3		$	0.7		$	0.6
Interest cost	0.7			0.9			1.3			1.7
Amortization:
Prior service credit	(1.5		)	(2.9		)	(3.0		)	(5.7		)
Net actuarial loss	0.6			0.7			1.1			1.3
Net periodic benefit cost (income)	$	0.2		$	(1.0	)	$	0.1		$	(2.1	)