Annual report pursuant to Section 13 and 15(d)

Asset Retirement Obligations - Additional Information (Detail)

v2.4.0.8
Asset Retirement Obligations - Additional Information (Detail) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Asset Retirement Obligations [Line Items]    
Reduction in asset retirement obligations $ 81,543,000 $ 112,827,000
Reduction in asset retirement obligations including plug and abandon wells and facilities damaged by hurricane 11,600,000 29,600,000
Liabilities assumed through acquisition 4,233,000 31,664,000
Liabilities settled (81,543,000) (112,827,000)
Hurricane Ike
   
Asset Retirement Obligations [Line Items]    
Revisions of estimated liabilities 6,801,000 (20,616,000)
All Other
   
Asset Retirement Obligations [Line Items]    
Revisions of estimated liabilities $ 37,779,000 $ 74,075,000