Suspended Exploratory Well Costs - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014 Well	Dec. 31, 2013	Dec. 31, 2014 Scenario, Forecast Well
Projects With Exploratory Well Costs Capitalized For More Than One Year [Line Items]
Capitalized exploratory well costs that have been capitalized for a period greater than one year	$ 35,584	$ 6,964
Number of wells waiting on pipeline	1
Number of wells expected to be producing within next quarter			4

The amount of exploratory well costs that have been capitalized for a period of greater than one year after the completion of drilling.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 235

-Section 50

-Paragraph 1B

-Subparagraph b

-URI http://asc.fasb.org/extlink&oid=8451039&loc=SL6806780-109447

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