Acquisitions (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended				12 Months Ended
	Mar. 31, 2012 Operations	Mar. 31, 2011	Mar. 31, 2012 Oil and Gas [Member]	Mar. 31, 2012 Oakleaf [Member]	Dec. 31, 2011 Oakleaf [Member]	Dec. 31, 2010 Oakleaf [Member]	Jul. 28, 2011 Oakleaf [Member]
Acquisitions and Divestitures (Textual) [Abstract]
Acquisition cost of acquired entity				$ 432	$ 432		$ 432
Cash received in acquisition							4
Operating revenues	3,295	3,103				580
Acquisition-related costs classified as Selling, general and administrative expenses					1
Revenues recognized by acquiree post the acquisition date				148
Net losses recognized by acquiree post the acquisition date				less than $1 million
Purchase price allocation to goodwill				327	327
Total consideration, net of cash acquired, for business acquisition	$ 129	$ 99	$ 94
Number of collection and recycling operations acquired	8