XML 72 R35.htm IDEA: XBRL DOCUMENT

Asset Retirement Obligations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Changes in Company's asset retirement obligations
Asset retirement obligations at the beginning of the period			$ 15,245
Liabilities incurred			509
Liabilities assumed in Anadarko Basin Acquisition			6,296
Current period accretion expense	313	164	567	298
Asset retirement obligations at the end of the period	$ 22,617		$ 22,617

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

+ References+ Details