Income Taxes (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets net noncurrent classification [Abstract]
Foreign Oil and Gas Exploration and Development Costs Deducted for Tax Over (Under) Book Depreciation, Depletion and Amortization	$ (112,346,000)				$ 25,592,000				$ (112,346,000)	$ 25,592,000
Foreign Net Operating Loss	369,257,000				164,829,000				369,257,000	164,829,000
Foreign Other	4,179,000				1,607,000				4,179,000	1,607,000
Foreign Valuation Allowances	(183,122,000)				(134,792,000)				(183,122,000)	(134,792,000)
Total Net Noncurrent Deferred Income Tax Assets	77,968,000				57,236,000				77,968,000	57,236,000
Deferred tax liabilities net current classification [Abstract]
Commodity Hedging Contracts	29,582,000				(57,754,000)				29,582,000	(57,754,000)
Deferred Compensation Plans	42,296,000				35,715,000				42,296,000	35,715,000
Net Operating Loss	96,616,000				0				96,616,000	0
Alternative Minimum Tax Credit Carryforward	72,297,000				0				72,297,000	0
Timing Differences Associated With Different Year-ends in Foreign Jurisdictions	0				(2,762,000)				0	(2,762,000)
Other	3,815,000				1,963,000				3,815,000	1,963,000
Total Net Current Deferred Income Tax Assets	244,606,000				0				244,606,000	0
Total Net Current Deferred Income Tax Liabilities	0				(22,838,000)				0	(22,838,000)
Deferred tax liabilities net noncurrent classification [Abstract]
Oil and Gas Exploration and Development Costs Deducted for Tax Over Book Depreciation, Depletion and Amortization	6,287,541,000				5,300,115,000				6,287,541,000	5,300,115,000
Non-Producing Leasehold Costs	(50,581,000)				(61,512,000)				(50,581,000)	(61,512,000)
Seismic Costs Capitalized for Tax	(136,964,000)				(125,026,000)				(136,964,000)	(125,026,000)
Equity Awards	(122,665,000)				(116,666,000)				(122,665,000)	(116,666,000)
Capitalized Interest	101,006,000				102,677,000				101,006,000	102,677,000
Net Operating Loss	0				(308,154,000)				0	(308,154,000)
Alternative Minimum Tax Credit Carryforward	(557,352,000)				(476,505,000)				(557,352,000)	(476,505,000)
Other	1,369,000				12,467,000				1,369,000	12,467,000
Total Net Noncurrent Deferred Income Tax Liabilities	5,522,354,000				4,327,396,000				5,522,354,000	4,327,396,000
Total Net Deferred Income Tax Liabilities	5,199,780,000				4,292,998,000				5,199,780,000	4,292,998,000
Income Before Income Taxes [Abstract]
United States									3,268,727,000	1,988,105,000	2,156,147,000
Foreign									168,159,000	(707,365,000)	(246,348,000)
Income (Loss) Before Income Taxes	919,082,000	721,555,000	1,035,230,000	761,019,000	(445,822,000)	560,189,000	646,239,000	520,134,000	3,436,886,000	1,280,740,000	1,909,799,000
Current income tax provision [Abstract]
Federal									207,777,000	242,674,000	94,244,000
State									22,856,000	22,573,000	1,083,000
Foreign									134,379,000	152,276,000	224,049,000
Total									365,012,000	417,523,000	319,376,000
Deferred income tax provision [Abstract]
Federal									915,994,000	454,173,000	608,181,000
State									26,305,000	632,000	40,321,000
Foreign									(67,534,000)	(161,867,000)	(149,202,000)
Total									874,765,000	292,938,000	499,300,000
Income Tax Provision									1,239,777,000	710,461,000	818,676,000
Effective income tax rate [Abstract]
Statutory Federal Income Tax Rate (in hundredths)									35.00%	35.00%	35.00%
State Income Tax, Net of Federal Benefit (in hundredths)									0.93%	1.18%	1.41%
Income Tax Provision Related to Foreign Operations (in hundredths)									(0.20%)	1.38%	0.88%
Income Tax Provision Related to Trinidad Operations (in hundredths)									0.43%	(0.27%)	3.37%
Canadian Valuation Allowances (in hundredths)									0.00%	10.57%	0.00%
Canadian Natural Gas Impairments (in hundredths)									0.00%	6.90%	1.85%
Other (in hundredths)									(0.09%)	0.71%	0.36%
Effective Income Tax Rate (in hundredths)									36.07%	55.47%	42.87%
Canadian statutory rate (in hundredths)										26.00%
Additional income tax provision related to valuation allowances recorded to reduce value of foreign deferred tax assets	183,000,000				158,000,000				183,000,000	158,000,000
Unrecognized tax benefits balance	0				33,000,000				0	33,000,000
Foreign subsidiaries' undistributed earnings	2,700,000,000								2,700,000,000
Regular tax net operating loss utilized									787,000,000
Balance of federal net operating loss expected to be carried forward									314,000,000
State Income Tax Net Operating Losses									700,000,000
Tax benefit reflected in additional paid-in-capital due to current year utilization of net operating losses	15,000,000								15,000,000
Additional tax benefit to be reflected in additional paid-in-capital due to future utilization of net operating losses	16,000,000								16,000,000
Alternative minimum tax paid									161,000,000
AMT Paid In Years Prior To Prior Reporting Period									469,000,000
Tax net operating loss incurred in United Kingdom in current year									282,000,000
Balance of tax net operating loss incurred in the United Kingdom in prior years									$ 267,000,000