Condensed Consolidating Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 398	$ 258	$ 282	$ 539
Other current assets	2,261	2,121
Total current assets	2,659	2,379
Property and equipment, net	12,518	12,242
Other assets	7,896	7,948
Total assets	23,073	22,569
Current liabilities:
Current portion of long-term debt	826	631
Accounts payable and other current liabilities	2,361	2,437
Total current liabilities	3,187	3,068
Long-term debt, less current portion	9,166	9,125
Other liabilities	4,108	3,986
Total liabilities	16,461	16,179
Equity:
Stockholders' equity	6,288	6,070
Noncontrolling interests	324	320
Total equity	6,612	6,390
Total liabilities and equity	23,073	22,569
WM [Member]
Current assets:
Cash and cash equivalents	270	119	184	465
Other current assets		6
Total current assets	270	125
Investments in and advances to affiliates	12,412	12,006
Other assets	47	120
Total assets	12,729	12,251
Current liabilities:
Current portion of long-term debt	401	298
Accounts payable and other current liabilities	75	124
Total current liabilities	476	422
Long-term debt, less current portion	5,923	5,727
Other liabilities	42	32
Total liabilities	6,441	6,181
Equity:
Stockholders' equity	6,288	6,070
Total equity	6,288	6,070
Total liabilities and equity	12,729	12,251
WM Holdings [Member]
Current assets:
Investments in and advances to affiliates	16,417	14,905
Other assets	12	12
Total assets	16,429	14,917
Current liabilities:
Accounts payable and other current liabilities	5	13
Total current liabilities	5	13
Long-term debt, less current portion	449	449
Total liabilities	454	462
Equity:
Stockholders' equity	15,975	14,455
Total equity	15,975	14,455
Total liabilities and equity	16,429	14,917
Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	128	139	98	74
Other current assets	2,261	2,115
Total current assets	2,389	2,254
Property and equipment, net	12,518	12,242
Investments in and advances to affiliates	3,446	3,033
Other assets	7,837	7,816
Total assets	26,190	25,345
Current liabilities:
Current portion of long-term debt	425	333
Accounts payable and other current liabilities	2,281	2,300
Total current liabilities	2,706	2,633
Long-term debt, less current portion	2,794	2,949
Other liabilities	4,066	3,954
Total liabilities	9,566	9,536
Equity:
Stockholders' equity	16,300	15,489
Noncontrolling interests	324	320
Total equity	16,624	15,809
Total liabilities and equity	26,190	25,345
Eliminations [Member]
Current assets:
Investments in and advances to affiliates	(32,275)	(29,944)
Total assets	(32,275)	(29,944)
Equity:
Stockholders' equity	(32,275)	(29,944)
Total equity	(32,275)	(29,944)
Total liabilities and equity	$ (32,275)	$ (29,944)