Quarterly Financial Data (Unaudited) - Schedule of Unaudited Quarterly Financial Data (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Information [Line Items]
Total operating revenues	$ 3,434	$ 3,461	$ 3,459	$ 3,295	$ 3,406	$ 3,522	$ 3,347	$ 3,103	$ 13,649	$ 13,378	$ 12,515
Income from operations	484	500	466	401	552	543	506	427	1,851	2,028	2,116
Consolidated net income	235	223	219	183	278	285	250	196	860	1,009	1,002
Net income attributable to Waste Management, Inc.	$ 224	$ 214	$ 208	$ 171	$ 266	$ 272	$ 237	$ 186	$ 817	$ 961	$ 953
Basic earnings per common share	$ 0.48	$ 0.46	$ 0.45	$ 0.37	$ 0.58	$ 0.58	$ 0.50	$ 0.39	$ 1.76	$ 2.05	$ 1.98
Diluted earnings per common share	$ 0.48	$ 0.46	$ 0.45	$ 0.37	$ 0.58	$ 0.58	$ 0.50	$ 0.39	$ 1.76	$ 2.04	$ 1.98