Property, Plant and Equipment (Narrative) (Details) - USD ($)	1 Months Ended	12 Months Ended			13 Months Ended
	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2012
Property Plant And Equipment [Line Items]
Proceeds from sales of property, plant and equipment		$ 423,911,000	$ 1,467,046,000	$ 1,650,000
Total capitalized exploratory well costs		130,514,000	120,455,000	393,030,000	$ 130,514,000	$ 445,697,000
Impairment of assets		2,493,156,000	$ 51,314,000	$ 21,587,000
Malaysia [Member]
Property Plant And Equipment [Line Items]
Percentage of interest in oil and gas property sold during period	10.00%		20.00%		30.00%
Proceeds from sales of property, plant and equipment	$ 417,200,000		$ 1,460,425,000
Gain (loss) on sale of assets, net of taxes		218,800,000	$ 321,454,000
Impairment of assets		$ 1,480,600,000