Condensed Consolidating Financial Statements - Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Income Statements, Captions [Line Items]
Operating revenues	$ 3,822	$ 3,716	$ 11,072	$ 10,833
Costs and expenses	3,123	3,015	9,050	8,901
Income from operations	699	701	2,022	1,932
Other income (expense):
Interest expense, net	(93)	(90)	(277)	(272)
Other, net	(9)	(8)	(28)	(53)
Total other income (expense)	(102)	(98)	(305)	(325)
Income before income taxes	597	603	1,717	1,607
Income tax expense (benefit)	99	215	325	561
Consolidated net income	498	388	1,392	1,046
Less: Net income (loss) attributable to noncontrolling interests	(1)	2	(2)
Net income attributable to Waste Management, Inc.	499	386	1,394	1,046
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues	(44)		(132)
Costs and expenses	(44)		(132)
Other income (expense):
Equity in earnings of subsidiaries, net of tax	(1,181)	(867)	(3,334)	(2,371)
Total other income (expense)	(1,181)	(867)	(3,334)	(2,371)
Income before income taxes	(1,181)	(867)	(3,334)	(2,371)
Consolidated net income	(1,181)	(867)	(3,334)	(2,371)
Net income attributable to Waste Management, Inc.	(1,181)	(867)	(3,334)	(2,371)
WM [Member] | Reportable Legal Entities [Member]
Condensed Income Statements, Captions [Line Items]
Costs and expenses	44		132
Income from operations	(44)		(132)
Other income (expense):
Interest expense, net	(78)	(75)	(232)	(223)
Equity in earnings of subsidiaries, net of tax	589	432	1,662	1,181
Total other income (expense)	511	357	1,430	958
Income before income taxes	467	357	1,298	958
Income tax expense (benefit)	(32)	(29)	(96)	(88)
Consolidated net income	499	386	1,394	1,046
Net income attributable to Waste Management, Inc.	499	386	1,394	1,046
WM Holdings [Member] | Reportable Legal Entities [Member]
Other income (expense):
Interest expense, net	(6)	(5)	(15)	(15)
Equity in earnings of subsidiaries, net of tax	592	435	1,672	1,190
Total other income (expense)	586	430	1,657	1,175
Income before income taxes	586	430	1,657	1,175
Income tax expense (benefit)	(2)	(2)	(4)	(6)
Consolidated net income	588	432	1,661	1,181
Net income attributable to Waste Management, Inc.	588	432	1,661	1,181
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Income Statements, Captions [Line Items]
Operating revenues	3,866	3,716	11,204	10,833
Costs and expenses	3,123	3,015	9,050	8,901
Income from operations	743	701	2,154	1,932
Other income (expense):
Interest expense, net	(9)	(10)	(30)	(34)
Other, net	(9)	(8)	(28)	(53)
Total other income (expense)	(18)	(18)	(58)	(87)
Income before income taxes	725	683	2,096	1,845
Income tax expense (benefit)	133	246	425	655
Consolidated net income	592	437	1,671	1,190
Less: Net income (loss) attributable to noncontrolling interests	(1)	2	(2)
Net income attributable to Waste Management, Inc.	$ 593	$ 435	$ 1,673	$ 1,190