Pro Forma Consolidated Results of Operations (Detail) (Oakleaf [Member], USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2011
Oakleaf [Member]
Business Acquisition [Line Items]
Operating revenues	$ 3,566	$ 10,287
Net income attributable to Waste Management, Inc.	$ 272	$ 689
Basic earnings per common share	$ 0.58	$ 1.46
Diluted earnings per common share	$ 0.58	$ 1.45