Supplemental Information on Oil and Natural Gas Operations - Unaudited - Financial Data Related to Oil and Gas Producing Activities (non-printing) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Extractive Industries [Abstract]
Asset retirement costs included in development cost	$ (43,901)	$ (20,305)	$ 54,737

The amount of asset retirement costs previously incurred and capitalized separately from the capitalized amount of the associated long-lived assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e61901-109447

Name:	us-gaap_CapitalizedCostsAssetRetirementCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant