Segment Information (Amounts Related To Balance Sheets For Each Segment) (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
External Revenues	$ 639	$ 511	$ 1,179	$ 886
Intersegment Revenues	0	0	0	0
Segment Margin	194	175	347	296
Operation and maintenance, including related party amounts of $–, $3, $– and $18	73	57	142	98
Gathering and Processing
External Revenues	583	462	1,069	787
Intersegment Revenues	0	0	0	0
Segment Margin	145	130	248	204
Operation and maintenance, including related party amounts of $–, $3, $– and $18	60	47	114	76
Natural Gas Transportation
External Revenues	0	0	0	0
Intersegment Revenues	0	0	0	0
Segment Margin	0	0	0	1
Operation and maintenance, including related party amounts of $–, $3, $– and $18	0	0	0	0
NGL Services
External Revenues	0	0	0	0
Intersegment Revenues	0	0	0	0
Segment Margin	0	0	0	0
Operation and maintenance, including related party amounts of $–, $3, $– and $18	0	0	0	0
Contract Services
External Revenues	52	44	101	90
Intersegment Revenues	4	5	7	10
Segment Margin	49	45	97	92
Operation and maintenance, including related party amounts of $–, $3, $– and $18	17	15	35	32
Corporate
External Revenues	4	5	9	9
Intersegment Revenues	0	0	0	0
Segment Margin	4	5	9	9
Operation and maintenance, including related party amounts of $–, $3, $– and $18	0	0	0	0
Eliminations
External Revenues	0	0	0	0
Intersegment Revenues	(4)	(5)	(7)	(10)
Segment Margin	(4)	(5)	(7)	(10)
Operation and maintenance, including related party amounts of $–, $3, $– and $18	$ (4)	$ (5)	$ (7)	$ (10)