Segment Information - Table (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total Revenues	$ 1,953	$ 3,218
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(921)	(5,092)
TOTAL ASSETS	15,357		$ 17,314
Oil And Gas Exploration And Production [Member]
Segment Reporting Information [Line Items]
Total Revenues	993	1,543
Marketing, Gathering And Compression [Member]
Segment Reporting Information [Line Items]
Total Revenues	960	1,675
Other Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	0	0
Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Total Revenues	1,953	3,218
Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	0	0
Operating Segments [Member] | Reportable Subsegments [Member] | Oil And Gas Exploration And Production [Member]
Segment Reporting Information [Line Items]
Total Revenues	993	1,520
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(895)	(5,349)
TOTAL ASSETS	12,624		14,610
Operating Segments [Member] | Reportable Subsegments [Member] | Oil And Gas Exploration And Production [Member] | Scenario, Previously Reported [Member]
Segment Reporting Information [Line Items]
TOTAL ASSETS			11,776
Operating Segments [Member] | Reportable Subsegments [Member] | Marketing, Gathering And Compression [Member]
Segment Reporting Information [Line Items]
Total Revenues	1,743	2,908
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	40	4
TOTAL ASSETS	1,425		1,524
Operating Segments [Member] | Reportable Subsegments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	0	0
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(9)	(14)
TOTAL ASSETS	1,468		1,491
Operating Segments [Member] | Reportable Subsegments [Member] | Other Segments [Member] | Scenario, Previously Reported [Member]
Segment Reporting Information [Line Items]
TOTAL ASSETS			4,325
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	(783)	0
Intersegment Eliminations [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Total Revenues	0	(1,210)
Intersegment Eliminations [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	783	1,210
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	(57)	267
TOTAL ASSETS	(160)		$ (311)
Intersegment Eliminations [Member] | Intersubsegment Eliminations [Member] | Oil And Gas Exploration And Production [Member]
Segment Reporting Information [Line Items]
Total Revenues	0	23
Intersegment Eliminations [Member] | Intersubsegment Eliminations [Member] | Marketing, Gathering And Compression [Member]
Segment Reporting Information [Line Items]
Total Revenues	(783)	(1,233)
Intersegment Eliminations [Member] | Intersubsegment Eliminations [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	$ 0	$ 0