Suspended Exploratory Well Costs (Details Textuals) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Suspended Exploratory Well Costs (Textuals) [Abstract]
Capitalized exploratory well costs that have been capitalized for more than one year	$ 5,233	$ 10,727
Number of Marcellus Shale wells	2

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 FASB Staff Position (FSP)
-Number FAS19-1
-Paragraph 10
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: 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=6821537&loc=SL6806780-109447

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