Condensed Consolidating Financial Statements - Statements of Operations (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Income Statements, Captions [Line Items]
Operating revenues		$ 3,946	$ 3,739	$ 7,642	$ 7,250
Costs and expenses		3,250	3,024	6,325	5,927
Income from operations		696	715	1,317	1,323
Other income (expense):
Interest expense, net		(100)	(93)	(196)	(184)
Loss on early extinguishment of debt	$ (84)	(84)		(84)
Other, net		(15)	(13)	(78)	(19)
Total other income (expense)		(199)	(106)	(358)	(203)
Income before income taxes		497	609	959	1,120
Income tax expense (benefit)		115	110	230	226
Consolidated net income		382	499	729	894
Less: Net income (loss) attributable to noncontrolling interests		1		1	(1)
Net income attributable to Waste Management, Inc.		381	499	728	895
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues		(46)	(44)	(92)	(88)
Costs and expenses		(46)	(44)	(92)	(88)
Other income (expense):
Equity in earnings of subsidiaries, net of tax		(1,075)	(1,179)	(1,962)	(2,153)
Total other income (expense)		(1,075)	(1,179)	(1,962)	(2,153)
Income before income taxes		(1,075)	(1,179)	(1,962)	(2,153)
Consolidated net income		(1,075)	(1,179)	(1,962)	(2,153)
Net income attributable to Waste Management, Inc.		(1,075)	(1,179)	(1,962)	(2,153)
WM [Member] | Reportable Legal Entities [Member]
Condensed Income Statements, Captions [Line Items]
Costs and expenses		46	44	92	88
Income from operations		(46)	(44)	(92)	(88)
Other income (expense):
Interest expense, net		(86)	(78)	(166)	(154)
Loss on early extinguishment of debt		(70)		(70)
Equity in earnings of subsidiaries, net of tax		530	588	970	1,073
Total other income (expense)		374	510	734	919
Income before income taxes		328	466	642	831
Income tax expense (benefit)		(53)	(33)	(86)	(64)
Consolidated net income		381	499	728	895
Net income attributable to Waste Management, Inc.		381	499	728	895
WM Holdings [Member] | Reportable Legal Entities [Member]
Other income (expense):
Interest expense, net		(5)	(4)	(10)	(9)
Loss on early extinguishment of debt		(14)		(14)
Equity in earnings of subsidiaries, net of tax		545	591	992	1,080
Other, net		(1)		(4)
Total other income (expense)		525	587	964	1,071
Income before income taxes		525	587	964	1,071
Income tax expense (benefit)		(5)	(1)	(6)	(2)
Consolidated net income		530	588	970	1,073
Net income attributable to Waste Management, Inc.		530	588	970	1,073
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues		3,992	3,783	7,734	7,338
Costs and expenses		3,250	3,024	6,325	5,927
Income from operations		742	759	1,409	1,411
Other income (expense):
Interest expense, net		(9)	(11)	(20)	(21)
Other, net		(14)	(13)	(74)	(19)
Total other income (expense)		(23)	(24)	(94)	(40)
Income before income taxes		719	735	1,315	1,371
Income tax expense (benefit)		173	144	322	292
Consolidated net income		546	591	993	1,079
Less: Net income (loss) attributable to noncontrolling interests		1		1	(1)
Net income attributable to Waste Management, Inc.		$ 545	$ 591	$ 992	$ 1,080