Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2014

Asset Retirement Obligation Disclosure [Abstract]

Schedule of changes in asset retirement obligations

Changes in asset retirement obligations for the years ended December 31, 2014 and 2013 were as follows:

(In millions)	2014			2013
Balance at beginning of year	$	27.7		$	13.0
Accretion expense	0.9			1.1
Payments	(2.2		)	(0.8		)
Revision of estimates	(1.0		)	13.8
Liabilities incurred	—			0.6
Balance at end of year	$	25.4		$	27.7