XML 74 R35.htm IDEA: XBRL DOCUMENT v2.4.0.8
Other Long-Term Obligations and Commitments - Reconciliation of Liability for Plugging and Abandonment Costs (Detail) (USD $)
In Thousands, unless otherwise specified
9 Months Ended
Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]  
Asset retirement obligation - December 31, 2012 $ 9,012
Liabilities incurred 165
Liabilities settled (811)
Accretion expense 283
Revisions in estimated liabilities 1,791
Asset retirement obligation - September 30, 2013 $ 10,440