Utility Regulatory Assets and Liabilities and Regulatory Matters (Tables)

6 Months Ended

Mar. 31, 2012

Utility Regulatory Assets and Liabilities and Regulatory Matters [Abstract]

Regulatory assets and liabilities associated with Gas Utility and Electric Utility

	March 31,		September 30,		March 31,
	2012		2011		2011
Regulatory assets:
Income taxes recoverable	$	99.2	$	97.9	$	89.9
Underfunded pension and postretirement plans		146.6		150.7		116.0
Environmental costs		18.2		19.5		22.0
Deferred fuel and power costs		11.0		12.2		8.2
Removal costs, net		11.9		12.3		11.7
Other		8.8		7.8		8.6
Total regulatory assets	$	295.7	$	300.4	$	256.4
Regulatory liabilities:
Postretirement benefits	$	12.1	$	11.5	$	11.2
Environmental overcollections		3.8		4.7		6.8
Deferred fuel and power refunds		12.0		6.6		34.0
State tax benefits—distribution system repairs		6.7		6.3		6.3
Other		0.8		0.7		—
Total regulatory liabilities	$	35.4	$	29.8	$	58.3