Commitments and Contingencies - Changes to Net Insurance Liabilities (Parenthetical) (Detail)	12 Months Ended
Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Expected time period in years for cash settlement of substantially all recorded obligations associated with insurance liabilities	5 years

Expected time period in years for cash settlement of substantially all recorded obligations associated with insurance liabilities.

No definition available.

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