Investment In Unconsolidated Affiliates Selected I/S Data for each of the Unconsolidated Affiliates (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
HPC [Member]
Total revenues	$ 38	$ 37
Operating income (loss)	22	18
Net income (loss)	19	15
MEP {Member]
Total revenues	62	66
Operating income (loss)	31	34
Net income (loss)	23	21
Lone Star {Member]
Total revenues	803	813
Operating income (loss)	97	84
Net income (loss)	97	83
Ranch JV {Member]
Total revenues	8	9
Operating income (loss)	5	7
Net income (loss)	5	6
Aqua - PVR [Member]
Total revenues	0
Operating income (loss)	(2)
Net income (loss)	$ (2)