Investment In Unconsolidated Affiliates (Condensed Consolidated Income Statements) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
HPC [Member]
Equity method investments, total revenues	$ 38	$ 46	$ 78	$ 88
Equity method investments, operating income	19	27	39	50
Equity method investments, net income	18	26	38	49
MEP
Equity method investments, total revenues	63	65	128	131
Equity method investments, operating income	33	34	67	68
Equity method investments, net income	21	21	42	42
Lone Star
Equity method investments, total revenues	425	158	783	325
Equity method investments, operating income	45	40	101	79
Equity method investments, net income	44	41	99	79
Ranch JV
Equity method investments, total revenues	3	0	6	0
Equity method investments, operating income	1	0	1	0
Equity method investments, net income	1	0	1	0
Grey Ranch JV [Member]
Equity method investments, total revenues	0	0	0	0
Equity method investments, operating income	(1)	0	(1)	0
Equity method investments, net income	$ (1)	$ 0	$ (1)	$ 0