Condensed Consolidating Statements of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Consolidated net income	$ 625	$ 731
Other adjustments	1,093	1,006
Net cash provided by (used in) operating activities	1,718	1,737
Cash flows from investing activities:
Acquisitions of businesses, net of cash acquired	(178)	(645)
Capital expenditures	(1,132)	(909)
Proceeds from divestitures of businesses (net of cash divested) and other sales of assets	28	22
Net receipts from restricted trust and escrow accounts and other, net	(79)	(3)
Net cash used in investing activities	(1,361)	(1,535)
Cash flows from financing activities:
New borrowings	685	1,001
Debt repayments	(473)	(425)
Common stock repurchases		(528)
Cash dividends	(493)	(481)
Exercise of common stock options	39	40
Distributions paid to noncontrolling interests and other	23	(66)
Net cash provided by (used in) financing activities	(219)	(459)
Effect of exchange rate changes on cash and cash equivalents	2
Increase (decrease) in cash and cash equivalents	140	(257)
Cash and cash equivalents at beginning of period	258	539
Cash and cash equivalents at end of period	398	282
WM [Member]
Cash flows from operating activities:
Consolidated net income	593	695
Equity in earnings of subsidiaries, net of taxes	(755)	(850)
Other adjustments	75	8
Net cash provided by (used in) operating activities	(87)	(147)
Cash flows from investing activities:
Net receipts from restricted trust and escrow accounts and other, net		(5)
Net cash used in investing activities		(5)
Cash flows from financing activities:
New borrowings	645	893
Debt repayments	(335)
Common stock repurchases		(528)
Cash dividends	(493)	(481)
Exercise of common stock options	39	40
Distributions paid to noncontrolling interests and other	14	(10)
(Increase) decrease in intercompany and investments, net	368	(43)
Net cash provided by (used in) financing activities	238	(129)
Increase (decrease) in cash and cash equivalents	151	(281)
Cash and cash equivalents at beginning of period	119	465
Cash and cash equivalents at end of period	270	184
WM Holdings [Member]
Cash flows from operating activities:
Consolidated net income	755	850
Equity in earnings of subsidiaries, net of taxes	(770)	(865)
Other adjustments	(8)	(11)
Net cash provided by (used in) operating activities	(23)	(26)
Cash flows from financing activities:
Debt repayments		(147)
(Increase) decrease in intercompany and investments, net	23	173
Net cash provided by (used in) financing activities	23	26
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Consolidated net income	802	901
Other adjustments	1,026	1,009
Net cash provided by (used in) operating activities	1,828	1,910
Cash flows from investing activities:
Acquisitions of businesses, net of cash acquired	(178)	(645)
Capital expenditures	(1,132)	(909)
Proceeds from divestitures of businesses (net of cash divested) and other sales of assets	28	22
Net receipts from restricted trust and escrow accounts and other, net	(79)	2
Net cash used in investing activities	(1,361)	(1,530)
Cash flows from financing activities:
New borrowings	40	108
Debt repayments	(138)	(278)
Distributions paid to noncontrolling interests and other	9	(56)
(Increase) decrease in intercompany and investments, net	(391)	(130)
Net cash provided by (used in) financing activities	(480)	(356)
Effect of exchange rate changes on cash and cash equivalents	2
Increase (decrease) in cash and cash equivalents	(11)	24
Cash and cash equivalents at beginning of period	139	74
Cash and cash equivalents at end of period	128	98
Eliminations [Member]
Cash flows from operating activities:
Consolidated net income	(1,525)	(1,715)
Equity in earnings of subsidiaries, net of taxes	$ 1,525	$ 1,715