Name:	cwst_ContractSettlementCharge
Namespace Prefix:	cwst_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Acquisition And Financing Costs And Other Items, Acquisition Activities

No definition available.

Name:	cwst_ExpenseFromAcquisitionAndFinancingCostsAndOtherItemsAcquisitionActivities
Namespace Prefix:	cwst_
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Period Type:	duration

The aggregate (recovery) charge associated with the closure of a landfill, which is comprised of an asset impairment charge, a development project charge write-off, an environmental remediation charge, a legal settlement charge, related legal and transaction costs and a recovery on insurance settlement. A positive number is an expense and a negative number is a gain.

No definition available.

Name:	cwst_LandfillClosureSettlementChargeNet
Namespace Prefix:	cwst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

Name:	us-gaap_EnvironmentalRemediationObligationsAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_LegalFees
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Balance Type:	debit
Period Type:	duration

The amount of loss pertaining to the specified contingency that was charged against earnings in the period, including the effects of revisions in previously reported estimates.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Name:	us-gaap_LossContingencyLossInPeriod
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The expense charged against earnings to eliminate the capitalized costs of projects that have been terminated during the reporting period, which is added back to net income when calculating cash provided by (used in) operations using the indirect method.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Name:	us-gaap_NoncashProjectAbandonmentCosts
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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.