Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2012

Asset Retirement Obligations

Schedule of changes in the entity's AROs

	(in millions)
Obligation at December 31, 2011	$	131.6
Accretion expense		7.2
Liabilities incurred		0.9
Expenditures		(4.9	)
Changes in estimate		(11.2	)
Obligation at September 30, 2012	$	123.6

Schedule of AROs reported in accrued expenses and other noncurrent liabilities on the entity's consolidated balance sheet

	September 30, 2012		December 31, 2011
	(in millions)
Current portion	$	11.0	$	13.8
Noncurrent portion		112.6		117.8
	$	123.6	$	131.6