Segment Information - Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 Segment	Mar. 31, 2014
Segment Reporting Information [Line Items]
Number of reportable segments	2
Total Revenues	$ 2,760	$ 5,046
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	0	0
Marketing, Gathering And Compression [Member]
Segment Reporting Information [Line Items]
Total Revenues	1,675	3,015
Marketing, Gathering And Compression [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	(1,233)	(2,408)
Oilfield Services [Member]
Segment Reporting Information [Line Items]
Total Revenues	0	239
Oilfield Services [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	$ 0	$ (271)