Segment Reporting Table (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 4,867	$ 2,970	$ 12,965	$ 8,778
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	387	(3,231)	1,561	(1,537)
TOTAL ASSETS	42,288		42,288		41,611
Exploration and Production
Segment Reporting Information [Line Items]
Revenues	1,586	1,437	5,444	4,622
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	430	(3,073)	654	(1,896)
TOTAL ASSETS	35,919		35,919		37,004
Marketing, Gathering And Compression
Segment Reporting Information [Line Items]
Revenues	3,032	1,381	6,871	3,710
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	128	120	395	1,279
TOTAL ASSETS	2,323		2,323		2,291
Oilfield Services
Segment Reporting Information [Line Items]
Revenues	245	152	636	446
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	(37)	(2)	(12)	96
TOTAL ASSETS	1,981		1,981		2,115
Other Operations
Segment Reporting Information [Line Items]
Revenues	4	0	14	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	(48)	(152)	808	(654)
TOTAL ASSETS	5,014		5,014		2,529
Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Revenues	4,867	2,970	12,965	8,778
Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments [Member] | Reportable Subsegments [Member] | Exploration and Production
Segment Reporting Information [Line Items]
Revenues	1,586	1,437	5,444	4,622
Operating Segments [Member] | Reportable Subsegments [Member] | Marketing, Gathering And Compression
Segment Reporting Information [Line Items]
Revenues	5,034	2,922	12,553	7,587
Operating Segments [Member] | Reportable Subsegments [Member] | Oilfield Services
Segment Reporting Information [Line Items]
Revenues	551	482	1,677	1,434
Operating Segments [Member] | Reportable Subsegments [Member] | Other Operations
Segment Reporting Information [Line Items]
Revenues	4	0	27	0
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	(86)	(124)	(284)	(362)
TOTAL ASSETS	(2,949)		(2,949)		(2,328)
Intersegment Eliminations [Member] | Exploration and Production
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Intersegment Eliminations [Member] | Marketing, Gathering And Compression
Segment Reporting Information [Line Items]
Revenues	(2,002)	(1,541)	(5,682)	(3,877)
Intersegment Eliminations [Member] | Oilfield Services
Segment Reporting Information [Line Items]
Revenues	(306)	(330)	(1,041)	(988)
Intersegment Eliminations [Member] | Other Operations
Segment Reporting Information [Line Items]
Revenues	0	0	(13)	0
Intersegment Eliminations [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Revenues	(2,308)	(1,871)	(6,736)	(4,865)
Intersegment Eliminations [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	$ 2,308	$ 1,871	$ 6,736	$ 4,865