Condensed Consolidating Financial Statements - Statements of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	$ 531	$ 435	$ 1,373	$ 1,140
Less: Comprehensive income (loss) attributable to noncontrolling interests	(1)	2	(2)
Comprehensive income attributable to Waste Management, Inc.	532	433	1,375	1,140
Eliminations [Member]
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	(1,181)	(867)	(3,334)	(2,371)
Comprehensive income attributable to Waste Management, Inc.	(1,181)	(867)	(3,334)	(2,371)
WM [Member] \| Reportable Legal Entities [Member]
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	501	388	1,400	1,052
Comprehensive income attributable to Waste Management, Inc.	501	388	1,400	1,052
WM Holdings [Member] \| Reportable Legal Entities [Member]
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	588	432	1,661	1,181
Comprehensive income attributable to Waste Management, Inc.	588	432	1,661	1,181
Non-Guarantor Subsidiaries [Member] \| Reportable Legal Entities [Member]
Condensed Statement Of Income Captions [Line Items]
Comprehensive income	623	482	1,646	1,278
Less: Comprehensive income (loss) attributable to noncontrolling interests	(1)	2	(2)
Comprehensive income attributable to Waste Management, Inc.	$ 624	$ 480	$ 1,648	$ 1,278

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e557-108580

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4613674-111683

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4569643-111683

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 55
-Paragraph 4K
-URI http://asc.fasb.org/extlink&oid=84234705&loc=SL4591552-111686

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4569616-111683

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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