Condensed Consolidating Financial Statements - Balance Sheets (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 2,915		$ 61	$ 83
Other current assets	2,645		2,584
Total current assets	5,560		2,645
Property and equipment, net	12,805		11,942
Other assets	8,744		8,063
Total assets	27,109		22,650
Current liabilities:
Current portion of long-term debt	211		432
Accounts payable and other current liabilities	2,778		2,676
Total current liabilities	2,989		3,108
Long-term debt, less current portion	13,147		9,594
Other liabilities	4,186		3,672
Total liabilities	20,322		16,374
Equity:
Stockholders' equity	6,785		6,275
Noncontrolling interests	2		1
Total equity	6,787	$ 6,467	6,276	$ 6,241	$ 6,056	$ 6,042
Total liabilities and equity	27,109		22,650
Eliminations [Member]
Current assets:
Other current assets	(46)
Total current assets	(46)
Investments in affiliates	(52,307)		(49,773)
Advances to affiliates	(17,930)		(17,258)
Total assets	(70,283)		(67,031)
Current liabilities:
Accounts payable and other current liabilities	(46)
Total current liabilities	(46)
Due to affiliates	(24,936)		(24,253)
Total liabilities	(24,982)		(24,253)
Equity:
Stockholders' equity	(52,307)		(49,773)
Advances to affiliates	7,006		6,995
Total equity	(45,301)		(42,778)
Total liabilities and equity	(70,283)		(67,031)
WM [Member] | Reportable Legal Entities [Member]
Current assets:
Cash and cash equivalents	2,863
Other current assets	48		2
Total current assets	2,911		2
Investments in affiliates	25,940		24,676
Other assets	5		8
Total assets	28,856		24,686
Current liabilities:
Current portion of long-term debt	14		258
Accounts payable and other current liabilities	113		82
Total current liabilities	127		340
Long-term debt, less current portion	10,611		7,377
Due to affiliates	18,039		17,398
Other liabilities	3		5
Total liabilities	28,780		25,120
Equity:
Stockholders' equity	6,785		6,275
Advances to affiliates	(6,709)		(6,709)
Total equity	76		(434)
Total liabilities and equity	28,856		24,686
WM Holdings [Member] | Reportable Legal Entities [Member]
Current assets:
Other current assets	4		5
Total current assets	4		5
Investments in affiliates	26,367		25,097
Other assets	10		31
Total assets	26,381		25,133
Current liabilities:
Accounts payable and other current liabilities	7		9
Total current liabilities	7		9
Long-term debt, less current portion	248		304
Due to affiliates	188		146
Total liabilities	443		459
Equity:
Stockholders' equity	25,938		24,674
Total equity	25,938		24,674
Total liabilities and equity	26,381		25,133
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Current assets:
Cash and cash equivalents	52		61
Other current assets	2,639		2,577
Total current assets	2,691		2,638
Property and equipment, net	12,805		11,942
Advances to affiliates	17,930		17,258
Other assets	8,729		8,024
Total assets	42,155		39,862
Current liabilities:
Current portion of long-term debt	197		174
Accounts payable and other current liabilities	2,704		2,585
Total current liabilities	2,901		2,759
Long-term debt, less current portion	2,288		1,913
Due to affiliates	6,709		6,709
Other liabilities	4,183		3,667
Total liabilities	16,081		15,048
Equity:
Stockholders' equity	26,369		25,099
Advances to affiliates	(297)		(286)
Noncontrolling interests	2		1
Total equity	26,074		24,814
Total liabilities and equity	$ 42,155		$ 39,862