Asset Retirement Obligation (Tables)

12 Months Ended

Dec. 31, 2014

Asset Retirement Obligation Disclosure [Abstract]

Asset Retirement Obligation

Activity related to the Company's asset retirement obligations is as follows:

(In thousands)	Year Ended   December 31, 2014
Balance at beginning of period	$	75,853
Liabilities incurred	7,220
Liabilities settled and divested	(1,474		)
Liabilities acquired	1,206
Accretion expense	5,110
Change in estimate	38,740
Balance at end of period	$	126,655