Acquisitions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2013	Jun. 18, 2012
Business Acquisition [Line Items]
Fair value of Land and Building at the time of Acquisition	$ 8.5
Purchase Consideration	8.5
Cash consideration transferred		$ 26.4
Block Deep Water Pompano Field Mississippi Canyon [Member]
Business Acquisition [Line Items]
Percentage of working interest acquired		25.00%
Mississippi Canyon Block 29 [Member]
Business Acquisition [Line Items]
Percentage of working interest acquired		14.00%
Mississippi Canyon Block 72 [Member]
Business Acquisition [Line Items]
Percentage of working interest acquired		10.00%

Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6910749&loc=d3e4845-128472

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 55

-Paragraph 37

-URI http://asc.fasb.org/extlink&oid=25498275&loc=d3e2207-128464

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