Geographic Operating Segment Information (Schedule Of Income Statement By Geographic Operating Segment) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Oil and gas	$ 583,931	$ 422,042	$ 1,081,061	$ 894,087
Interest and other	18,454	16,952	51,141	34,960
Gain (loss) on disposition of assets, net	(296)	7,645	(2,487)	24,588
Revenues and other income	602,089	446,639	1,129,715	953,635
Oil and gas production	102,455	94,012	202,386	180,112
Production and ad valorem taxes	35,864	25,338	69,160	52,399
Depletion, depreciation and amortization	153,898	144,309	294,271	288,737
Exploration and abandonments	19,914	22,743	37,557	39,591
General and administrative	44,644	40,433	88,750	78,748
Accretion of discount on asset retirement obligations	2,658	2,529	5,313	5,388
Interest	45,768	45,368	90,995	92,891
Hurricane activity, net	(2)	5,184	69	(2,226)
Derivative (gains) losses, net	(229,478)	(177,528)	14,954	(443,004)
Other	14,388	14,193	32,269	30,139
Costs and expenses, Total	190,109	216,581	835,724	322,775
Income from continuing operations before income taxes	411,980	230,058	293,991	630,860
Income tax provision	(144,696)	(83,220)	(97,545)	(227,227)
Income from continuing operations	267,284	146,838	196,446	403,633
United States [Member]
Oil and gas	562,411	401,540	1,038,140	848,204
Interest and other	13,725	998	16,603	1,507
Gain (loss) on disposition of assets, net		7,560		24,979
Revenues and other income	576,136	410,098	1,054,743	874,690
Oil and gas production	101,741	93,116	200,576	178,440
Production and ad valorem taxes	35,864	25,338	69,160	52,399
Depletion, depreciation and amortization	127,864	117,859	244,404	233,364
Exploration and abandonments	19,731	22,689	37,216	39,465
Accretion of discount on asset retirement obligations	2,047	1,907	4,091	4,144
Hurricane activity, net	(2)	5,184	69	(2,226)
Other	5,410	10,270	10,569	20,551
Costs and expenses, Total	292,655	276,363	566,085	526,137
Income from continuing operations before income taxes	283,481	133,735	488,658	348,553
Income tax provision	(104,888)	(49,482)	(180,803)	(128,965)
Income from continuing operations	178,593	84,253	307,855	219,588
South Africa [Member]
Oil and gas	21,520	20,502	42,921	45,883
Revenues and other income	21,520	20,502	42,921	45,883
Oil and gas production	714	896	1,810	1,672
Depletion, depreciation and amortization	13,536	18,442	27,221	40,339
Exploration and abandonments	183	54	341	126
Accretion of discount on asset retirement obligations	611	622	1,222	1,244
Costs and expenses, Total	15,044	20,014	30,594	43,381
Income from continuing operations before income taxes	6,476	488	12,327	2,502
Income tax provision	(1,813)	(137)	(3,452)	(701)
Income from continuing operations	4,663	351	8,875	1,801
Headquarters [Member]
Interest and other	4,729	15,954	34,538	33,453
Gain (loss) on disposition of assets, net	(296)	85	(2,487)	(391)
Revenues and other income	4,433	16,039	32,051	33,062
Depletion, depreciation and amortization	12,498	8,008	22,646	15,034
General and administrative	44,644	40,433	88,750	78,748
Interest	45,768	45,368	90,995	92,891
Derivative (gains) losses, net	(229,478)	(177,528)	14,954	(443,004)
Other	8,978	3,923	21,700	9,588
Costs and expenses, Total	(117,590)	(79,796)	239,045	(246,743)
Income from continuing operations before income taxes	122,023	95,835	(206,994)	279,805
Income tax provision	(37,995)	(33,601)	86,710	(97,561)
Income from continuing operations	$ 84,028	$ 62,234	$ (120,284)	$ 182,244