Condensed Consolidating Financial Statements - Balance Sheets (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Current assets:
Cash and cash equivalents	$ 83	$ 22	$ 35
Other current assets	2,592	2,602
Total current assets	2,675	2,624
Property and equipment, net	11,815	11,559
Other assets	8,101	7,646
Total assets	22,591	21,829
Current liabilities:
Current portion of long-term debt	447	739
Accounts payable and other current liabilities	2,623	2,523
Total current liabilities	3,070	3,262
Long-term debt, less current portion	9,569	8,752
Other liabilities	3,711	3,773
Total liabilities	16,350	15,787
Equity:
Stockholders' equity	6,239	6,019
Noncontrolling interests	2	23
Total equity	6,241	6,042
Total liabilities and equity	22,591	21,829
Eliminations [Member]
Current assets:
Investments in affiliates	(48,599)	(45,286)
Advances to affiliates	(16,289)	(15,349)
Total assets	(64,888)	(60,635)
Current liabilities:
Due to affiliates	(22,645)	(21,701)
Total liabilities	(22,645)	(21,701)
Equity:
Stockholders' equity	(48,599)	(45,286)
Advances to affiliates	6,356	6,352
Total equity	(42,243)	(38,934)
Total liabilities and equity	(64,888)	(60,635)
WM [Member] | Reportable Legal Entities [Member]
Current assets:
Other current assets	46	5
Total current assets	46	5
Investments in affiliates	24,055	22,393
Other assets	7	9
Total assets	24,108	22,407
Current liabilities:
Current portion of long-term debt	104	537
Accounts payable and other current liabilities	71	55
Total current liabilities	175	592
Long-term debt, less current portion	7,409	6,457
Due to affiliates	16,353	15,404
Other liabilities	5	8
Total liabilities	23,942	22,461
Equity:
Stockholders' equity	6,239	6,019
Advances to affiliates	(6,073)	(6,073)
Total equity	166	(54)
Total liabilities and equity	24,108	22,407
WM Holdings [Member] | Reportable Legal Entities [Member]
Current assets:
Other current assets	5	5
Total current assets	5	5
Investments in affiliates	24,544	22,893
Other assets	31	31
Total assets	24,580	22,929
Current liabilities:
Accounts payable and other current liabilities	4	9
Total current liabilities	4	9
Long-term debt, less current portion	304	304
Due to affiliates	219	224
Total liabilities	527	537
Equity:
Stockholders' equity	24,053	22,392
Total equity	24,053	22,392
Total liabilities and equity	24,580	22,929
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Current assets:
Cash and cash equivalents	83	22
Other current assets	2,541	2,592
Total current assets	2,624	2,614
Property and equipment, net	11,815	11,559
Advances to affiliates	16,289	15,349
Other assets	8,063	7,606
Total assets	38,791	37,128
Current liabilities:
Current portion of long-term debt	343	202
Accounts payable and other current liabilities	2,548	2,459
Total current liabilities	2,891	2,661
Long-term debt, less current portion	1,856	1,991
Due to affiliates	6,073	6,073
Other liabilities	3,706	3,765
Total liabilities	14,526	14,490
Equity:
Stockholders' equity	24,546	22,894
Advances to affiliates	(283)	(279)
Noncontrolling interests	2	23
Total equity	24,265	22,638
Total liabilities and equity	$ 38,791	$ 37,128