Defined Benefit Pension and Other Postretirement Plans (Tables)

9 Months Ended

Jun. 30, 2011

Employee Retirement Plans [Abstract]

Components of net periodic pension expense and other postretirement benefit costs

							Other
	Pension Benefits						Postretirement Benefits
	Three Months Ended						Three Months Ended
	June 30,						June 30,
	2011			2010			2011			2010
Service cost	$	2.1		$	2.2		$	0.1		$	0.1
Interest cost		6.1			5.8			0.3			0.3
Expected return on assets		(6.4	)		(6.5	)		(0.1	)		(0.1	)
Amortization of:
Prior service cost (benefit)		0.1			—			(0.2	)		(0.1	)
Actuarial loss		1.7			1.5			0.1			0.1
Net benefit cost		3.6			3.0			0.2			0.3
Change in associated regulatory liabilities		—			—			0.8			0.7
Net expense	$	3.6		$	3.0		$	1.0		$	1.0

							Other
	Pension Benefits						Postretirement Benefits
	Nine Months Ended						Nine Months Ended
	June 30,						June 30,
	2011			2010			2011			2010
Service cost	$	6.6		$	6.5		$	0.4		$	0.3
Interest cost		18.1			17.6			0.8			0.9
Expected return on assets		(19.4	)		(19.4	)		(0.4	)		(0.3	)
Amortization of:
Prior service cost (benefit)		0.2			—			(0.5	)		(0.3	)
Actuarial loss		5.7			4.4			0.3			0.2
Net benefit cost		11.2			9.1			0.6			0.8
Change in associated regulatory liabilities		—			—			2.4			2.2
Net expense	$	11.2		$	9.1		$	3.0		$	3.0

Reconciliation of the projected benefit obligation

	Three Months
	Ended
	December 31,
	2010
Change in benefit obligations:
Benefit obligations — October 1, 2010	$	465.0
Service cost		2.2
Interest cost		5.8
Actuarial gain		(30.6	)
Benefits paid		(4.7	)
Benefit obligations — December 31, 2010	$	437.7
Change in plan assets:
Fair value of plan assets — October 1, 2010	$	287.9
Actual gain on assets		19.3
Employer contributions		1.8
Benefits paid		(4.7	)
Fair value of plan assets — December 31, 2010	$	304.3
Funded status of the merged plan — December 31, 2010	$	(133.4	)
At December 31, 2010:
Liabilities recorded in the balance sheet:
Unfunded liabilities — included in other current liabilities	$	(20.3	)
Unfunded liabilities — included in other noncurrent liabilities		(113.1	)
Net amount recognized	$	(133.4	)
Amounts recorded in regulatory assets and liabilities:
Prior service cost	$	0.3
Net actuarial loss		112.7
Total	$	113.0
Amounts recorded in stockholders’ equity:
Prior service cost	$	0.1
Net actuarial loss		9.8
Total	$	9.9