Segment Information - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) Segment	Mar. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	2
Total Revenues	$ 1,953	$ 3,218
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	(783)	0
Marketing, Gathering And Compression [Member]
Segment Reporting Information [Line Items]
Total Revenues	960	1,675
Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	0	0
Intersubsegment Eliminations [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	783	1,210
Intersubsegment Eliminations [Member] | Marketing, Gathering And Compression [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Revenues	$ (783)	$ (1,233)