Final price paid per share for the purchase of the targeted number of shares, determined by an average market price over a fixed period of time.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 25

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6405686&loc=d3e22802-112653

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of a stock repurchase plan authorized by an entity's Board of Directors.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Accelerated share repurchase percentage of shares to be repurchased.

+ References

No definition available.

+ Details

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Namespace Prefix:	wm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Accelerated share repurchases settlement payment or receipt of shares.

+ References

No definition available.

+ Details

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Namespace Prefix:	wm_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of banks with accelerated share repurchase agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	wm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

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Capital Stock, Dividends and Share Repurchases - Stock Repurchase Programs (Parenthetical) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended		1 Months Ended	3 Months Ended	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Feb. 28, 2014	Sep. 30, 2014 Financial_Institutions	Feb. 28, 2015
Stock Repurchase Program [Line Items]
Shares repurchased	9,569,000	5,368,000
Accelerated Share Repurchase Agreements (ASRs) [Member]
Stock Repurchase Program [Line Items]
Maximum capital allocated for repurchases of common stock			$ 600
Shares repurchased				9,600,000
Common stock repurchases				$ 600
Number of banks in which ASR agreement signed				2
Percentage of common stock shares repurchased				70.00%
Accelerated Share Repurchase Agreements (ASRs) [Member] \| Subsequent Event [Member]
Stock Repurchase Program [Line Items]
Final weighted average per share purchase price for the completed ASR agreements					$ 48.58
Shares received from the banks to settle the ASRs					2,800,000