Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2015

Asset Retirement Obligation Disclosure [Abstract]

Reconciliations of the Company's ARO liability

Reconciliations of the Company’s asset retirement obligations are as follows:

	December 31,
	2015			2014
	(Dollars in millions)
Balance at beginning of year	$	752.5		$	712.8
Liabilities incurred or acquired	1.3			22.7
Liabilities settled or disposed	(53.3		)	(19.7		)
Accretion expense	42.7			39.3
Revisions to estimates	(31.1		)	(2.6		)
Balance at end of year	$	712.1		$	752.5
Less: Current portion (included in "Accounts payable and accrued expenses")	25.5			30.2
Noncurrent obligation (included in "Asset Retirement Obligations")	686.6			722.3
Balance at end of year — active locations	$	656.8		$	676.2
Balance at end of year — closed or inactive locations	$	55.3		$	76.3