Oil and Gas Exploration and Production Industries Disclosures, Results Of Operations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Dry Hole Costs	$ 53,230	$ 72,486	$ 51,243
United States [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Crude Oil and Condensate, Natural Gas Liquids and Natural Gas Revenues	5,814,942	3,928,240	2,732,088
Other	32,329	19,886	9,692
Total	5,847,271	3,948,126	2,741,780
Exploration Costs	148,199	156,252	137,696
Dry Hole Costs	30,521	30,927	39,570
Transportation Costs	421,060	372,466	270,940
Production Costs	1,096,955	763,769	556,236
Impairments	575,976	271,466	272,195
Depreciation, Depletion and Amortization	2,011,080	1,430,408	1,188,243
Income (Loss) Before Income Taxes	1,563,480	922,838	276,900
Income Tax Provision (Benefit)	569,153	375,855	106,537
Results of Operations	994,327	546,983	170,363
Canada [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Crude Oil and Condensate, Natural Gas Liquids and Natural Gas Revenues	459,853	477,416	413,910
Other	258	(31)	(15)
Total	460,111	477,385	413,895
Exploration Costs	10,479	17,597	18,675
Dry Hole Costs	432	14,875	1,461
Transportation Costs	5,969	9,892	9,317
Production Costs	174,973	174,667	145,292
Impairments	452,103	451,703	32,996
Depreciation, Depletion and Amortization	258,772	314,663	210,509
Income (Loss) Before Income Taxes	(442,617)	(506,012)	(4,355)
Income Tax Provision (Benefit)	(121,044)	(151,315)	(1,276)
Results of Operations	(321,573)	(354,697)	(3,079)
Trinidad [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Crude Oil and Condensate, Natural Gas Liquids and Natural Gas Revenues	555,143	447,852	229,649
Other	586	3,696	3,500
Total	555,729	451,548	233,149
Exploration Costs	2,520	2,277	5,107
Dry Hole Costs	0	5,000	0
Transportation Costs	1,620	1,348	1,141
Production Costs	49,318	51,125	27,616
Impairments	0	1,465	0
Depreciation, Depletion and Amortization	106,802	70,553	46,608
Income (Loss) Before Income Taxes	395,469	319,780	152,677
Income Tax Provision (Benefit)	202,815	140,413	58,681
Results of Operations	192,654	179,367	93,996
Other International [Member]
Results of Operations for Oil and Gas Producing Activities, by Geographic Area [Line Items]
Crude Oil and Condensate, Natural Gas Liquids and Natural Gas Revenues	28,250	27,707	23,826
Other	0	0	0
Total	28,250	27,707	23,826
Exploration Costs	10,460	11,255	8,114
Dry Hole Costs	22,277	21,684	10,212
Transportation Costs	1,673	1,483	1,931
Production Costs	10,964	8,504	9,452
Impairments	2,958	418	641
Depreciation, Depletion and Amortization	17,160	15,399	7,966
Income (Loss) Before Income Taxes	(37,242)	(31,036)	(14,490)
Income Tax Provision (Benefit)	(13,056)	(14,245)	(6,067)
Results of Operations	$ (24,186)	$ (16,791)	$ (8,423)