Condensed Consolidating Financial Statements - Statements of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	$ 484	$ 531	$ 1,278	$ 1,373
Less: Comprehensive income (loss) attributable to noncontrolling interests		(1)	1	(2)
Comprehensive income attributable to Waste Management, Inc.	484	532	1,277	1,375
Eliminations [Member]
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	(1,269)	(1,181)	(3,231)	(3,334)
Comprehensive income attributable to Waste Management, Inc.	(1,269)	(1,181)	(3,231)	(3,334)
WM [Member] | Reportable Legal Entities [Member]
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	497	501	1,229	1,400
Comprehensive income attributable to Waste Management, Inc.	497	501	1,229	1,400
WM Holdings [Member] | Reportable Legal Entities [Member]
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	667	588	1,637	1,661
Comprehensive income attributable to Waste Management, Inc.	667	588	1,637	1,661
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	589	623	1,643	1,646
Less: Comprehensive income (loss) attributable to noncontrolling interests		(1)	1	(2)
Comprehensive income attributable to Waste Management, Inc.	$ 589	$ 624	$ 1,642	$ 1,648