Asset Impairments and Unusual Items (Detail) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($)
Asset Impairments and Unusual Items
Investment impairment	$ 52

The amount by which the fair value of an investment is less than the carrying amount of that investment and the decline in fair value is deemed to be other than temporary.

No definition available.

Name:	wm_InvestmentWithoutReadilyDeterminableFairValueOtherThanTemporaryImpairment
Namespace Prefix:	wm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration