Defined Benefit Pension and Other Postretirement Plans (Tables)

3 Months Ended

Dec. 31, 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 December 31,						Three Months Ended December 31,
	2013			2012			2013			2012
Service cost	$	2.3		$	2.8		$	0.1		$	0.2
Interest cost	6.4			5.9			0.2			0.2
Expected return on assets	(7.3		)	(6.9		)	(0.1		)	(0.1		)
Amortization of:
Prior service benefit	—			—			(0.1		)	(0.1		)
Actuarial loss	2.0			3.8			—			0.1
Net benefit cost	3.4			5.6			0.1			0.3
Change in associated regulatory liabilities	—			—			0.9			0.8
Net expense	$	3.4		$	5.6		$	1.0		$	1.1