Exploratory Well Costs (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 ExploratoryWell		Dec. 31, 2012 ExploratoryWell		Dec. 31, 2011 ExploratoryWell
Exploratory Well Costs [Abstract]
Balance at January 1	$ 49,116,000		$ 61,111,000		$ 99,801,000
Additions Pending the Determination of Proved Reserves	52,099,000		73,332,000		31,271,000
Reclassifications to Proved Properties	(54,505,000)		(69,462,000)		(29,227,000)
Costs Charged to Expense (1)	(35,859,000)	[1]	(17,115,000)	[1]	(42,178,000)	[1]
Foreign Currency Translations	(1,640,000)		1,250,000		1,444,000
Balance at December 31	9,211,000		49,116,000		61,111,000
Capitalized exploratory well costs that have been capitalized for a period less than one year	9,211,000		28,319,000		17,009,000
Capitalized exploratory well costs that have been capitalized for a period greater than one year	0		20,797,000	[2]	44,102,000	[3]
Number of exploratory wells that have been capitalized for a period greater than one year	0		1		4
Exploratory well costs related to an outside operated, offshore Central North Sea project in the United Kingdom					20,000,000
Exploratory well costs related to an East Irish Sea project in the United Kingdom					9,000,000
Exploratory well costs related to a project in the Sichuan Basin, Sichuan Province, China					9,000,000
Exploratory well costs related to a shale project in British Columbia, Canada					$ 6,000,000

[1] Includes capitalized exploratory well costs charged to either dry hole costs or impairments.

[2] Consists of costs related to an outside operated, offshore Central North Sea natural gas project in the United Kingdom (U.K.).

[3] Consists of costs related to an outside operated, offshore Central North Sea project in the U.K. ($20 million), an East Irish Sea project in the U.K. ($9 million), a project in the Sichuan Basin, Sichuan Province, China ($9 million), and a shale project in British Columbia, Canada ($6 million).