Segment and Related Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Reportable segments
Gross Operating Revenue	$ 4,052	$ 3,871	$ 7,865	$ 7,434
Intercompany Operating Revenues	(593)	(524)	(1,111)	(984)
Net Operating Revenues	3,459	3,347	6,754	6,450
Income from Operations	466	506	867	933
Eastern [Member]
Reportable segments
Gross Operating Revenue	780	800	1,516	1,504
Intercompany Operating Revenues	(148)	(136)	(276)	(248)
Net Operating Revenues	632	664	1,240	1,256
Income from Operations	143	141	274	261
Midwest [Member]
Reportable segments
Gross Operating Revenue	822	828	1,579	1,556
Intercompany Operating Revenues	(136)	(126)	(247)	(232)
Net Operating Revenues	686	702	1,332	1,324
Income from Operations	176	156	329	285
Southern [Member]
Reportable segments
Gross Operating Revenue	865	862	1,713	1,700
Intercompany Operating Revenues	(131)	(105)	(246)	(203)
Net Operating Revenues	734	757	1,467	1,497
Income from Operations	194	193	387	385
Western [Member]
Reportable segments
Gross Operating Revenue	836	825	1,632	1,615
Intercompany Operating Revenues	(126)	(114)	(238)	(222)
Net Operating Revenues	710	711	1,394	1,393
Income from Operations	145	142	276	282
Wheelabrator [Member]
Reportable segments
Gross Operating Revenue	206	226	413	436
Intercompany Operating Revenues	(32)	(30)	(62)	(61)
Net Operating Revenues	174	196	351	375
Income from Operations	15	42	19	55
Other [Member]
Reportable segments
Gross Operating Revenue	543	330	1,012	623
Intercompany Operating Revenues	(20)	(13)	(42)	(18)
Net Operating Revenues	523	317	970	605
Income from Operations	(54)	(21)	(72)	(35)
Operating Group Total [Member]
Reportable segments
Gross Operating Revenue	4,052	3,871	7,865	7,434
Intercompany Operating Revenues	(593)	(524)	(1,111)	(984)
Net Operating Revenues	3,459	3,347	6,754	6,450
Income from Operations	619	653	1,213	1,233
Corporate and Other [Member]
Reportable segments
Income from Operations	$ (153)	$ (147)	$ (346)	$ (300)