Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2015

Asset Retirement Obligation Disclosure [Abstract]

Changes in Asset Retirement Obligations

The change in our asset retirement obligations during the six months ended June 30, 2015 is set forth below:

	Six Months Ended June 30, 2015
	(In millions)
Asset retirement obligations as of the beginning of the period, including current portion	$	316.4
Liabilities incurred		3.5
Liabilities settled		(35.9	)
Accretion expense		12.8
Asset retirement obligations as of the end of the period, including current portion	$	296.8