Property, Plant And Equipment (Net Changes in Capitalized Exploratory Well Costs) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Property, Plant And Equipment [Abstract]
Beginning balance at January 1	$ 120,455us-gaap_CapitalizedExploratoryWellCosts	$ 393,030us-gaap_CapitalizedExploratoryWellCosts
Additions pending the determination of proved reserves	141	2,919
Ending balance at March 31	$ 120,596us-gaap_CapitalizedExploratoryWellCosts	$ 395,949us-gaap_CapitalizedExploratoryWellCosts

The amount of capitalized exploratory well costs that is pending the determination of proved reserves. This does not include amounts that were capitalized and subsequently expensed in the same annual period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 235

-Section 50

-Paragraph 1B

-Subparagraph (a)

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

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