Property, Plant and Equipment (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Total capitalized exploratory well costs	$ 122,075		$ 122,075	$ 396,406		$ 120,455	$ 393,030
Exploratory well costs capitalized more than one year	121,900		121,900
Proceeds from sales of property, plant and equipment			423,106	3,089	$ 1,880,000
Gain (loss) on sale of assets	18,246		154,123	$ (4,997)
United States [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Exploratory well costs capitalized more than one year	55,900		55,900
Brunei
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Exploratory well costs capitalized more than one year	$ 66,000		$ 66,000
Malaysia [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Percentage of interest in oil and gas property sold during period		30.00%
Proceeds from sales of property, plant and equipment		$ 417,200
Gain (loss) on sale of assets		$ 199,500