Condensed Consolidating Financial Statements - Condensed Consolidating Statements of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Consolidated net income	$ 1,338	$ 130	$ 860
Other adjustments	993	2,325	1,435
Net cash provided by (used in) operating activities	2,331	2,455	2,295
Cash flows from investing activities:
Acquisitions of businesses, net of cash acquired	(35)	(724)	(250)
Capital expenditures	(1,151)	(1,271)	(1,510)
Proceeds from divestitures of businesses and other assets (net of cash divested)	2,253	138	44
Net receipts from restricted trust and escrow accounts and other, net	(72)	(43)	(114)
Net cash provided by (used in) investing activities	995	(1,900)	(1,830)
Cash flows from financing activities:
New borrowings	2,817	2,232	1,620
Debt repayments	(3,568)	(2,077)	(1,498)
Common stock repurchases	(600)	(239)
Cash dividends	(693)	(683)	(658)
Exercise of common stock options	93	132	43
Acquisitions of and distributions paid to noncontrolling interests and other	(121)	(52)	(37)
Net cash provided by (used in) financing activities	(2,072)	(687)	(530)
Effect of exchange rate changes on cash and cash equivalents	(5)	(4)	1
Increase (decrease) in cash and cash equivalents	1,249	(136)	(64)
Cash and cash equivalents at beginning of year	58	194	258
Cash and cash equivalents at end of year	1,307	58	194
Eliminations [Member]
Cash flows from operating activities:
Consolidated net income	(2,580)	(645)	(2,080)
Equity in earnings of subsidiaries, net of taxes	2,580	645	2,080
WM [Member]
Cash flows from operating activities:
Consolidated net income	1,298	98	817
Equity in earnings of subsidiaries, net of taxes	(1,510)	(313)	(1,034)
Other adjustments	(36)	(2)	81
Net cash provided by (used in) operating activities	(248)	(217)	(136)
Cash flows from financing activities:
New borrowings	2,572	1,140	1,145
Debt repayments	(3,005)	(1,120)	(835)
Common stock repurchases	(600)	(239)
Cash dividends	(693)	(683)	(658)
Exercise of common stock options	93	132	43
Acquisitions of and distributions paid to noncontrolling interests and other	5	14	15
(Increase) decrease in intercompany and investments, net	3,111	913	367
Net cash provided by (used in) financing activities	1,483	157	77
Increase (decrease) in cash and cash equivalents	1,235	(60)	(59)
Cash and cash equivalents at beginning of year		60	119
Cash and cash equivalents at end of year	1,235		60
WM Holdings [Member]
Cash flows from operating activities:
Consolidated net income	1,510	313	1,034
Equity in earnings of subsidiaries, net of taxes	(1,070)	(332)	(1,046)
Other adjustments	(1)
Net cash provided by (used in) operating activities	439	(19)	(12)
Cash flows from investing activities:
Proceeds from divestitures of businesses and other assets (net of cash divested)	1,618
Net cash provided by (used in) investing activities	1,618
Cash flows from financing activities:
(Increase) decrease in intercompany and investments, net	(2,057)	19	12
Net cash provided by (used in) financing activities	(2,057)	19	12
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Consolidated net income	1,110	364	1,089
Other adjustments	1,030	2,327	1,354
Net cash provided by (used in) operating activities	2,140	2,691	2,443
Cash flows from investing activities:
Acquisitions of businesses, net of cash acquired	(35)	(724)	(250)
Capital expenditures	(1,151)	(1,271)	(1,510)
Proceeds from divestitures of businesses and other assets (net of cash divested)	635	138	44
Net receipts from restricted trust and escrow accounts and other, net	(72)	(43)	(114)
Net cash provided by (used in) investing activities	(623)	(1,900)	(1,830)
Cash flows from financing activities:
New borrowings	245	1,092	475
Debt repayments	(563)	(957)	(663)
Acquisitions of and distributions paid to noncontrolling interests and other	(126)	(66)	(52)
(Increase) decrease in intercompany and investments, net	(1,054)	(932)	(379)
Net cash provided by (used in) financing activities	(1,498)	(863)	(619)
Effect of exchange rate changes on cash and cash equivalents	(5)	(4)	1
Increase (decrease) in cash and cash equivalents	14	(76)	(5)
Cash and cash equivalents at beginning of year	58	134	139
Cash and cash equivalents at end of year	$ 72	$ 58	$ 134