Oil and Gas Exploration and Production Industries Disclosures, Costs Incurred (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
United States [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Acquisition Costs of Properties - Proved	$ 4,219,000	$ 0	$ 464,362,000
Acquisition Costs of Properties - Unproved	295,160,000	403,509,000	648,331,000
Exploration Costs	311,369,000	454,379,000	473,489,000
Development Costs	5,410,378,000	3,892,403,000	1,898,859,000
Total	6,021,126,000	4,750,291,000	3,485,041,000
Asset Retirement Costs Included In Development	52,000,000	71,000,000	60,000,000
Noncash acquisition costs			353,000,000
Canada [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Acquisition Costs of Properties - Proved	28,000	0	(33,000)
Acquisition Costs of Properties - Unproved	6,216,000	13,956,000	17,806,000
Exploration Costs	31,472,000	38,604,000	51,164,000
Development Costs	302,564,000	417,176,000	237,613,000
Total	340,280,000	469,736,000	306,550,000
Asset Retirement Costs Included In Development	70,000,000	2,000,000	18,000,000
Trinidad [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Acquisition Costs of Properties - Proved	0	0	0
Acquisition Costs of Properties - Unproved	0	0	800,000
Exploration Costs	2,549,000	23,386,000	14,263,000
Development Costs	138,905,000	114,986,000	27,369,000
Total	141,454,000	138,372,000	42,432,000
Asset Retirement Costs Included In Development	7,000,000	(3,000,000)	6,000,000
Other International [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Acquisition Costs of Properties - Proved	0	0	0
Acquisition Costs of Properties - Unproved	(604,000)	(107,000)	(311,000)
Exploration Costs	18,164,000	86,784,000	71,872,000
Development Costs	78,744,000	13,429,000	1,914,000
Total	96,304,000	100,106,000	73,475,000
Asset Retirement Costs Included In Development	$ 4,000,000	$ 2,000,000	$ 0