Oil Gas Reserve Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2013 MMcf	Dec. 31, 2012 MMcf	Dec. 31, 2011 MMcf
Reserve Quantities [Line Items]
Adoption of assumption due to revision of oil and gas reporting requirements	Using a historical 12-month average pricing assumption
Average 12-month oil prices net of differentials	102.21	101.20	100.97
Average 12-month gas prices net of differentials	3.66	2.68	4.74
Annual discount rate for discounting future cash flows	10.00%
Pyrenees project [Member]
Reserve Quantities [Line Items]
Acquisition of additional working interested in pyrenees project			15.00%
Purchase of producing properties			6
Pompano and Mica fields [Member]
Reserve Quantities [Line Items]
Purchase of producing properties			102
Appalachia drilling program [Member]
Reserve Quantities [Line Items]
Extensions, discoveries and other additions	117	162	94
Deep gas development project at LaCantera [Member]
Reserve Quantities [Line Items]
Extensions, discoveries and other additions		17	11
GOM drilling program at Mississippi Canyon Block 109 [Member]
Reserve Quantities [Line Items]
Extensions, discoveries and other additions			6
Sale of our non-operated interest in the Main Pass Block 296 and 311 fields [Member]
Reserve Quantities [Line Items]
Sale of reserves			13
Positive reserve report pricing changes [Member]
Reserve Quantities [Line Items]
Revisions of previous estimates	17.8
Well performance [Member]
Reserve Quantities [Line Items]
Revisions of previous estimates	54.5
Natural Gas Liquids (MBbls) [Member]
Reserve Quantities [Line Items]
Extensions, discoveries and other additions	4,395	4,856
Revisions of previous estimates	2,439	9,349	4,911
Purchase of producing properties		619
Average 12-month gas prices net of differentials	37.59	38.23	58.26