Consolidated Statements of Income and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net Operating Revenues
Crude Oil and Condensate	$ 5,659,437	$ 3,838,284	$ 1,998,771
Natural Gas Liquids	727,177	779,364	462,345
Natural Gas	1,571,762	2,240,540	2,420,099
Gains on Mark-to-Market Commodity Derivative Contracts	393,744	626,053	61,912
Gathering, Processing and Marketing	3,096,694	2,115,792	909,680
Gains on Asset Dispositions, Net	192,660	492,909	223,538
Other, Net	41,162	33,173	23,551
Total	11,682,636	10,126,115	6,099,896
Operating Expenses
Lease and Well	1,000,052	941,954	698,430
Transportation Costs	601,431	430,322	385,189
Gathering and Processing Costs	97,945	80,727	66,758
Exploration Costs	185,569	171,658	187,381
Dry Hole Costs	14,970	53,230	72,486
Impairments	1,270,735	1,031,037	742,647
Marketing Costs	3,035,494	2,072,137	884,212
Depreciation, Depletion and Amortization	3,169,703	2,516,381	1,941,926
General and Administrative	331,545	304,811	280,474
Taxes Other Than Income	495,395	410,549	317,074
Total	10,202,839	8,012,806	5,576,577
Operating Income	1,479,797	2,113,309	523,319
Other Income, Net	14,495	6,853	14,243
Income Before Interest Expense and Income Taxes	1,494,292	2,120,162	537,562
Interest Expense
Incurred	263,254	268,104	205,886
Capitalized	(49,702)	(57,741)	(76,300)
Net Interest Expense	213,552	210,363	129,586
Income Before Income Taxes	1,280,740	1,909,799	407,976
Income Tax Provision	710,461	818,676	247,322
Net Income	570,279	1,091,123	160,654
Net Income Per Share
Basic	$ 2.13	$ 4.15	$ 0.64
Diluted	$ 2.11	$ 4.10	$ 0.63
Dividends Declared per Common Share	$ 0.68	$ 0.64	$ 0.62
Average Number of Common Shares
Basic	267,577	262,735	250,876
Diluted	270,762	266,268	254,500
Comprehensive Income
Net Income	570,279	1,091,123	160,654
Other Comprehensive Income (Loss)
Foreign Currency Translation Adjustments	37,739	(32,597)	96,179
Foreign Currency Swap Transaction	1,589	(1,571)	4,447
Income Tax Related to Foreign Currency Swap Transaction	(404)	404	(1,203)
Interest Rate Swap Transaction	(134)	(5,223)	1,843
Income Tax Related to Interest Rate Swap Transaction	48	1,878	(664)
Other	(689)	(1,216)	(251)
Other Comprehensive Income (Loss)	38,149	(38,325)	100,351
Comprehensive Income	$ 608,428	$ 1,052,798	$ 261,005