Condensed Consolidating Financial Statements - Statements of Operations (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Income Statements, Captions [Line Items]
Operating revenues		$ 3,967	$ 3,822	$ 11,609	$ 11,072
Costs and expenses		3,233	3,123	9,558	9,050
Income from operations		734	699	2,051	2,022
Other income (expense):
Interest expense, net		(105)	(93)	(301)	(277)
Loss on early extinguishment of debt	$ (84)	(1)		(85)
Other, net		(13)	(9)	(91)	(28)
Total other income (expense)		(119)	(102)	(477)	(305)
Income before income taxes		615	597	1,574	1,717
Income tax expense (benefit)		120	99	350	325
Consolidated net income		495	498	1,224	1,392
Less: Net income (loss) attributable to noncontrolling interests			(1)	1	(2)
Net income attributable to Waste Management, Inc.		495	499	1,223	1,394
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues		(45)	(44)	(137)	(132)
Costs and expenses		(45)	(44)	(137)	(132)
Other income (expense):
Equity in earnings of subsidiaries, net of tax		(1,197)	(1,181)	(3,159)	(3,334)
Other, net		(72)		(72)
Total other income (expense)		(1,269)	(1,181)	(3,231)	(3,334)
Income before income taxes		(1,269)	(1,181)	(3,231)	(3,334)
Consolidated net income		(1,269)	(1,181)	(3,231)	(3,334)
Net income attributable to Waste Management, Inc.		(1,269)	(1,181)	(3,231)	(3,334)
WM [Member] | Reportable Legal Entities [Member]
Condensed Income Statements, Captions [Line Items]
Costs and expenses		45	44	137	132
Income from operations		(45)	(44)	(137)	(132)
Other income (expense):
Interest expense, net		(92)	(78)	(258)	(232)
Loss on early extinguishment of debt				(70)
Equity in earnings of subsidiaries, net of tax		595	589	1,565	1,662
Total other income (expense)		503	511	1,237	1,430
Income before income taxes		458	467	1,100	1,298
Income tax expense (benefit)		(37)	(32)	(123)	(96)
Consolidated net income		495	499	1,223	1,394
Net income attributable to Waste Management, Inc.		495	499	1,223	1,394
WM Holdings [Member] | Reportable Legal Entities [Member]
Other income (expense):
Interest expense, net		(5)	(6)	(15)	(15)
Loss on early extinguishment of debt				(14)
Equity in earnings of subsidiaries, net of tax		602	592	1,594	1,672
Other, net		72		68
Total other income (expense)		669	586	1,633	1,657
Income before income taxes		669	586	1,633	1,657
Income tax expense (benefit)		2	(2)	(4)	(4)
Consolidated net income		667	588	1,637	1,661
Net income attributable to Waste Management, Inc.		667	588	1,637	1,661
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues		4,012	3,866	11,746	11,204
Costs and expenses		3,233	3,123	9,558	9,050
Income from operations		779	743	2,188	2,154
Other income (expense):
Interest expense, net		(8)	(9)	(28)	(30)
Loss on early extinguishment of debt		(1)		(1)
Other, net		(13)	(9)	(87)	(28)
Total other income (expense)		(22)	(18)	(116)	(58)
Income before income taxes		757	725	2,072	2,096
Income tax expense (benefit)		155	133	477	425
Consolidated net income		602	592	1,595	1,671
Less: Net income (loss) attributable to noncontrolling interests			(1)	1	(2)
Net income attributable to Waste Management, Inc.		$ 602	$ 593	$ 1,594	$ 1,673