Defined Benefit Pension and Other Postretirement Plans (Tables)

9 Months Ended

Jun. 30, 2013

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Component of net periodic pension expense and other postretirement benefit costs

Net periodic pension expense and other postretirement benefit costs include the following components:

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended June 30,						Three Months Ended June 30,
	2013			2012			2013			2012
Service cost	$	2.8		$	2.1		$	0.2		$	0.1
Interest cost	5.9			6.1			0.2			0.2
Expected return on assets	(6.9		)	(6.4		)	(0.1		)	(0.1		)
Amortization of:
Prior service cost (benefit)	0.1			0.1			(0.1		)	(0.1		)
Actuarial loss	3.7			2.1			0.1			0.1
Net benefit cost	5.6			4.0			0.3			0.2
Change in associated regulatory liabilities	—			—			0.8			0.8
Net expense	$	5.6		$	4.0		$	1.1		$	1.0
	Pension Benefits						Other Postretirement Benefits
	Nine Months Ended						Nine Months Ended
	June 30,						June 30,
	2013			2012			2013			2012
Service cost	$	8.5		$	6.4		$	0.5		$	0.3
Interest cost	17.6			18.3			0.7			0.8
Expected return on assets	(20.7		)	(19.2		)	(0.4		)	(0.4		)
Amortization of:
Prior service cost (benefit)	0.2			0.2			(0.2		)	(0.3		)
Actuarial loss	11.2			6.3			0.3			0.3
Net benefit cost	16.8			12.0			0.9			0.7
Change in associated regulatory liabilities	—			—			2.4			2.3
Net expense	$	16.8		$	12.0		$	3.3		$	3.0