Defined Benefit Pension and Other Postretirement Plans (Tables)

6 Months Ended

Mar. 31, 2014

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

Components 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 March 31,						Three Months Ended March 31,
	2014			2013			2014			2013
Service cost	$	2.3		$	2.8		$	0.1		$	0.2
Interest cost	6.5			5.9			0.2			0.2
Expected return on assets	(7.3		)	(6.9		)	(0.1		)	(0.1		)
Amortization of:
Prior service cost (benefit)	0.1			0.1			(0.1		)	(0.1		)
Actuarial loss	1.9			3.7			—			0.1
Net benefit cost	3.5			5.6			0.1			0.3
Change in associated regulatory liabilities	—			—			0.9			0.8
Net expense	$	3.5		$	5.6		$	1.0		$	1.1
	Pension Benefits						Other Postretirement Benefits
	Six Months Ended						Six Months Ended
	March 31,						March 31,
	2014			2013			2014			2013
Service cost	$	4.7		$	5.7		$	0.3		$	0.3
Interest cost	12.9			11.8			0.5			0.5
Expected return on assets	(14.7		)	(13.8		)	(0.3		)	(0.3		)
Amortization of:
Prior service cost (benefit)	0.2			0.2			(0.2		)	(0.1		)
Actuarial loss	3.8			7.4			—			0.2
Net benefit cost	6.9			11.3			0.3			0.6
Change in associated regulatory liabilities	—			—			1.8			1.6
Net expense	$	6.9		$	11.3		$	2.1		$	2.2