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Subsidiary Guarantors - Schedule of Consolidating Statement of Operations (Detail) (USD $)
In Thousands, unless otherwise specified
2 Months Ended 3 Months Ended 8 Months Ended 12 Months Ended
Dec. 31, 2014
Oct. 31, 2014
Jul. 31, 2014
Apr. 30, 2014
Jan. 31, 2014
Oct. 31, 2013
Jul. 31, 2013
Apr. 30, 2013
Jan. 31, 2013
Oct. 31, 2012
Jul. 31, 2012
Apr. 30, 2012
Jan. 31, 2012
Oct. 31, 2011
Jul. 31, 2011
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2014
Apr. 30, 2014
Dec. 31, 2013
Apr. 30, 2013
Dec. 31, 2012
Apr. 30, 2012
Condensed Financial Statements, Captions [Line Items]                                              
Revenues $ 85,646us-gaap_Revenues $ 141,341us-gaap_Revenues $ 141,387us-gaap_Revenues $ 118,927us-gaap_Revenues $ 117,852us-gaap_Revenues $ 132,296us-gaap_Revenues $ 128,558us-gaap_Revenues $ 108,694us-gaap_Revenues $ 112,167us-gaap_Revenues $ 116,836us-gaap_Revenues $ 117,638us-gaap_Revenues $ 106,375us-gaap_Revenues $ 111,520us-gaap_Revenues $ 125,989us-gaap_Revenues $ 124,066us-gaap_Revenues $ 368,374us-gaap_Revenues $ 340,069us-gaap_Revenues   $ 497,633us-gaap_Revenues   $ 455,335us-gaap_Revenues   $ 467,950us-gaap_Revenues
Operating expenses:                                              
Cost of operations                               258,650us-gaap_CostOfGoodsAndServicesSold 236,076us-gaap_CostOfGoodsAndServicesSold   354,592us-gaap_CostOfGoodsAndServicesSold   323,014us-gaap_CostOfGoodsAndServicesSold   318,068us-gaap_CostOfGoodsAndServicesSold
General and administration                               45,732us-gaap_GeneralAndAdministrativeExpense 40,803us-gaap_GeneralAndAdministrativeExpense   61,865us-gaap_GeneralAndAdministrativeExpense   58,205us-gaap_GeneralAndAdministrativeExpense   60,264us-gaap_GeneralAndAdministrativeExpense
Depreciation and amortization                               41,485us-gaap_DepreciationDepletionAndAmortization 40,618us-gaap_DepreciationDepletionAndAmortization   60,339us-gaap_DepreciationDepletionAndAmortization   56,576us-gaap_DepreciationDepletionAndAmortization   58,415us-gaap_DepreciationDepletionAndAmortization
Asset impairment charge                                     7,455us-gaap_AssetImpairmentCharges       40,746us-gaap_AssetImpairmentCharges
Legal settlement                                             1,359us-gaap_LitigationSettlementAmount
Development project charge                                     1,394cwst_AbandonedDevelopmentProjectExpense       131cwst_AbandonedDevelopmentProjectExpense
Severance and reorganization costs                                 161us-gaap_SeveranceCosts1   586us-gaap_SeveranceCosts1   3,709us-gaap_SeveranceCosts1    
Environmental remediation charge                               950us-gaap_EnvironmentalRemediationExpense 400us-gaap_EnvironmentalRemediationExpense   400us-gaap_EnvironmentalRemediationExpense        
(Gain) expense from divestiture, acquisition and financing costs                               (553)cwst_DivestitureAcquisitionFinancingCosts 120cwst_DivestitureAcquisitionFinancingCosts   144cwst_DivestitureAcquisitionFinancingCosts   1,410cwst_DivestitureAcquisitionFinancingCosts    
Change in fair value of acquisition related contingent consideration                                     (1,058)cwst_GainLossOnSettlementOfContingentConsideration        
Total operating expenses                               346,264us-gaap_CostsAndExpenses 318,178us-gaap_CostsAndExpenses   485,717us-gaap_CostsAndExpenses   442,914us-gaap_CostsAndExpenses   478,983us-gaap_CostsAndExpenses
Operating income (loss) 2,708us-gaap_OperatingIncomeLoss 10,064us-gaap_OperatingIncomeLoss 9,338us-gaap_OperatingIncomeLoss (5,973)us-gaap_OperatingIncomeLoss (1,298)us-gaap_OperatingIncomeLoss 9,450us-gaap_OperatingIncomeLoss 9,737us-gaap_OperatingIncomeLoss 2,110us-gaap_OperatingIncomeLoss 78us-gaap_OperatingIncomeLoss 4,426us-gaap_OperatingIncomeLoss 5,807us-gaap_OperatingIncomeLoss (37,679)us-gaap_OperatingIncomeLoss 4,448us-gaap_OperatingIncomeLoss 11,730us-gaap_OperatingIncomeLoss 10,468us-gaap_OperatingIncomeLoss 22,110us-gaap_OperatingIncomeLoss 21,891us-gaap_OperatingIncomeLoss   11,916us-gaap_OperatingIncomeLoss   12,421us-gaap_OperatingIncomeLoss   (11,033)us-gaap_OperatingIncomeLoss
Other expense (income), net:                                              
Interest income                               (247)us-gaap_InterestIncomeOther (184)us-gaap_InterestIncomeOther   (312)us-gaap_InterestIncomeOther   (141)us-gaap_InterestIncomeOther   (42)us-gaap_InterestIncomeOther
Interest expense                               25,639us-gaap_InterestExpense 25,357us-gaap_InterestExpense   38,175us-gaap_InterestExpense   41,570us-gaap_InterestExpense   45,008us-gaap_InterestExpense
(Income) loss from equity method investments                                 (1,027)us-gaap_IncomeLossFromEquityMethodInvestments   (936)us-gaap_IncomeLossFromEquityMethodInvestments   (4,441)us-gaap_IncomeLossFromEquityMethodInvestments   (9,994)us-gaap_IncomeLossFromEquityMethodInvestments
(Gain) loss on sale of equity method investment                                 815us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal   593us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal        
Impairment of equity method investment                                             10,680us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment
Impairment of investments                               2,320us-gaap_ImpairmentOfInvestments             10,680us-gaap_ImpairmentOfInvestments
(Gain) loss on derivative instruments                               225us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet (69)us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet   280us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet   4,512us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet    
Loss on debt extinguishment                                         15,584us-gaap_GainsLossesOnExtinguishmentOfDebt   300us-gaap_GainsLossesOnExtinguishmentOfDebt
Other income                               (720)us-gaap_OtherNonoperatingIncome (603)us-gaap_OtherNonoperatingIncome   (1,059)us-gaap_OtherNonoperatingIncome   (1,036)us-gaap_OtherNonoperatingIncome   (863)us-gaap_OtherNonoperatingIncome
Other expense, net                               27,217us-gaap_NonoperatingIncomeExpense 24,713us-gaap_NonoperatingIncomeExpense   37,427us-gaap_NonoperatingIncomeExpense   64,930us-gaap_NonoperatingIncomeExpense   65,077us-gaap_NonoperatingIncomeExpense
Income (loss) from continuing operations before income taxes                               (5,107)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest (2,822)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest   (25,511)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest   (52,509)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest   (76,110)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Provision (benefit) for income taxes                               703us-gaap_IncomeTaxExpenseBenefit 1,162us-gaap_IncomeTaxExpenseBenefit   1,799us-gaap_IncomeTaxExpenseBenefit   (2,526)us-gaap_IncomeTaxExpenseBenefit   1,593us-gaap_IncomeTaxExpenseBenefit
Income (loss) from continuing operations (5,987)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest 259us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (290)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (11,815)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (10,750)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (294)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (142)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (9,696)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (11,079)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (20,732)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (8,155)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (48,985)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (24,517)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (693)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (3,502)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (5,810)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest (3,984)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest   (27,310)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest   (49,983)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest   (77,703)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
Discontinued operations:                                              
Income (loss) from discontinued operations , net                                 284us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax   284us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax   (4,480)us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax   (614)us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax
Gain (loss) on disposal of discontinued operations, net             (378)us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax                   (378)us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax   (378)us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax       725us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
Net income (loss) (6,017)us-gaap_ProfitLoss 361us-gaap_ProfitLoss (154)us-gaap_ProfitLoss (15,633)us-gaap_ProfitLoss (11,033)us-gaap_ProfitLoss (575)us-gaap_ProfitLoss (163)us-gaap_ProfitLoss (13,518)us-gaap_ProfitLoss (11,474)us-gaap_ProfitLoss (21,092)us-gaap_ProfitLoss (8,379)us-gaap_ProfitLoss (49,130)us-gaap_ProfitLoss (24,635)us-gaap_ProfitLoss (765)us-gaap_ProfitLoss (3,062)us-gaap_ProfitLoss (5,810)us-gaap_ProfitLoss (4,078)us-gaap_ProfitLoss (27,404)us-gaap_ProfitLoss (27,404)us-gaap_ProfitLoss (54,463)us-gaap_ProfitLoss (54,463)us-gaap_ProfitLoss (77,592)us-gaap_ProfitLoss (77,592)us-gaap_ProfitLoss
Less: Net income (loss) attributable to noncontrolling interest                               208us-gaap_NetIncomeLossAttributableToNoncontrollingInterest (355)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest   (4,309)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest   (321)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest   (6)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
Net income (loss) attributable to common stockholders (5,987)us-gaap_NetIncomeLoss 259us-gaap_NetIncomeLoss (290)us-gaap_NetIncomeLoss (11,815)us-gaap_NetIncomeLoss (10,750)us-gaap_NetIncomeLoss (339)us-gaap_NetIncomeLoss (191)us-gaap_NetIncomeLoss (13,397)us-gaap_NetIncomeLoss (11,407)us-gaap_NetIncomeLoss (20,967)us-gaap_NetIncomeLoss (8,371)us-gaap_NetIncomeLoss (49,124)us-gaap_NetIncomeLoss (24,635)us-gaap_NetIncomeLoss (765)us-gaap_NetIncomeLoss (3,062)us-gaap_NetIncomeLoss (6,018)us-gaap_NetIncomeLoss (3,723)us-gaap_NetIncomeLoss   (23,095)us-gaap_NetIncomeLoss   (54,142)us-gaap_NetIncomeLoss   (77,586)us-gaap_NetIncomeLoss
Parent [Member]                                              
Condensed Financial Statements, Captions [Line Items]                                              
Revenues                                                  
Operating expenses:                                              
Cost of operations                               175us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    (23)us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (295)us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  16us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
General and administration                               2,681us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    1,377us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  220us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  576us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Depreciation and amortization                               548us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    935us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  1,017us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  1,568us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Asset impairment charge                                                
Legal settlement                                             1,000us-gaap_LitigationSettlementAmount
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Development project charge                                                
Severance and reorganization costs                                      4us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  1,766us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
   
Environmental remediation charge                                                
(Gain) expense from divestiture, acquisition and financing costs                                           303cwst_DivestitureAcquisitionFinancingCosts
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
   
Change in fair value of acquisition related contingent consideration                                               
Total operating expenses                               3,404us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    2,293us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  3,011us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  3,160us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Operating income (loss)                               (3,404)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    (2,293)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (3,011)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (3,160)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Other expense (income), net:                                              
Interest income                                      (4)us-gaap_InterestIncomeOther
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (32,896)us-gaap_InterestIncomeOther
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (39,871)us-gaap_InterestIncomeOther
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Interest expense                               25,815us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    38,095us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  42,405us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  46,058us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(Income) loss from equity method investments                                      18,811us-gaap_IncomeLossFromEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (24,723)us-gaap_IncomeLossFromEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (66,832)us-gaap_IncomeLossFromEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(Gain) loss on sale of equity method investment                                                
Impairment of equity method investment                                               
(Income) loss from consolidated entities                               (26,148)cwst_IncomeLossFromSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
             
Impairment of investments                               2,320us-gaap_ImpairmentOfInvestments
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
             
(Gain) loss on derivative instruments                               225us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    280us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  4,512us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
   
Loss on debt extinguishment                                         15,584us-gaap_GainsLossesOnExtinguishmentOfDebt
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  300us-gaap_GainsLossesOnExtinguishmentOfDebt
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Other income                               (301)us-gaap_OtherNonoperatingIncome
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    (557)us-gaap_OtherNonoperatingIncome
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (671)us-gaap_OtherNonoperatingIncome
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (486)us-gaap_OtherNonoperatingIncome
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Other expense, net                               (1,911)us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    19,003us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  53,657us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  72,833us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Income (loss) from continuing operations before income taxes                               (5,315)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    (21,296)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (56,668)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (75,993)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Provision (benefit) for income taxes                               703us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    1,799us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (2,526)us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  1,593us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Income (loss) from continuing operations                                      (23,095)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (54,142)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (77,586)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Discontinued operations:                                              
Income (loss) from discontinued operations , net                                                  
Gain (loss) on disposal of discontinued operations, net                                                  
Net income (loss)                               (6,018)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (23,095)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(23,095)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(54,142)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(54,142)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(77,586)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(77,586)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Less: Net income (loss) attributable to noncontrolling interest                                                  
Net income (loss) attributable to common stockholders                               (6,018)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
    (23,095)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (54,142)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
  (77,586)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Guarantors [Member]                                              
Condensed Financial Statements, Captions [Line Items]                                              
Revenues                               367,576us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    495,391us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  453,589us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  467,950us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Operating expenses:                                              
Cost of operations                               258,142us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    351,829us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  321,382us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  318,047us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
General and administration                               43,011us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    60,446us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  57,898us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  59,677us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Depreciation and amortization                               40,942us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    58,651us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  55,142us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  56,850us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Asset impairment charge                                              40,746us-gaap_AssetImpairmentCharges
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Legal settlement                                             359us-gaap_LitigationSettlementAmount
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Development project charge                                     1,394cwst_AbandonedDevelopmentProjectExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
      131cwst_AbandonedDevelopmentProjectExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Severance and reorganization costs                                      582us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  1,943us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
   
Environmental remediation charge                               950us-gaap_EnvironmentalRemediationExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    400us-gaap_EnvironmentalRemediationExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
       
(Gain) expense from divestiture, acquisition and financing costs                               (553)cwst_DivestitureAcquisitionFinancingCosts
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    144cwst_DivestitureAcquisitionFinancingCosts
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  1,107cwst_DivestitureAcquisitionFinancingCosts
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
   
Change in fair value of acquisition related contingent consideration                                     (1,058)cwst_GainLossOnSettlementOfContingentConsideration
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
       
Total operating expenses                               342,492us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    472,388us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  437,472us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  475,810us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Operating income (loss)                               25,084us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    23,003us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  16,117us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (7,860)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Other expense (income), net:                                              
Interest income                               (247)us-gaap_InterestIncomeOther
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    (308)us-gaap_InterestIncomeOther
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (113)us-gaap_InterestIncomeOther
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (34)us-gaap_InterestIncomeOther
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Interest expense                               (176)us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    80us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  32,033us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  38,813us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
(Income) loss from equity method investments                                      169us-gaap_IncomeLossFromEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (36)us-gaap_IncomeLossFromEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  7us-gaap_IncomeLossFromEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
(Gain) loss on sale of equity method investment                                                
Impairment of equity method investment                                               
(Income) loss from consolidated entities                                               
Impairment of investments                                               
(Gain) loss on derivative instruments                                                 
Loss on debt extinguishment                                                
Other income                               (419)us-gaap_OtherNonoperatingIncome
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    (501)us-gaap_OtherNonoperatingIncome
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (365)us-gaap_OtherNonoperatingIncome
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (377)us-gaap_OtherNonoperatingIncome
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Other expense, net                               (842)us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    (898)us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  31,591us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  38,395us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Income (loss) from continuing operations before income taxes                               25,926us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    23,901us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (15,474)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (46,255)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Provision (benefit) for income taxes                                                  
Income (loss) from continuing operations                                      23,901us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (15,474)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (46,255)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Discontinued operations:                                              
Income (loss) from discontinued operations , net                                      284us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (4,480)us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (614)us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationDuringPhaseOutPeriodNetOfTax
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Gain (loss) on disposal of discontinued operations, net                                      (378)us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
       725us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Net income (loss)                               25,926us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  23,807us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
23,807us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
(19,954)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
(19,954)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
(46,144)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
(46,144)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Less: Net income (loss) attributable to noncontrolling interest                                                  
Net income (loss) attributable to common stockholders                               25,926us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
    23,807us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (19,954)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
  (46,144)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Non-Guarantors [Member]                                              
Condensed Financial Statements, Captions [Line Items]                                              
Revenues                               798us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    2,242us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  1,746us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    
Operating expenses:                                              
Cost of operations                               333us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    2,786us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  1,927us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  5us-gaap_CostOfGoodsAndServicesSold
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
General and administration                               40us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    42us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  87us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  11us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Depreciation and amortization                               (5)us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    753us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  417us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (3)us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Asset impairment charge                                     7,455us-gaap_AssetImpairmentCharges
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
        
Legal settlement                                               
Development project charge                                                
Severance and reorganization costs                                                 
Environmental remediation charge                                                
(Gain) expense from divestiture, acquisition and financing costs                                                 
Change in fair value of acquisition related contingent consideration                                               
Total operating expenses                               368us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    11,036us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  2,431us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  13us-gaap_CostsAndExpenses
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Operating income (loss)                               430us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    (8,794)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (685)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (13)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Other expense (income), net:                                              
Interest income                                                  
Interest expense                                                  
(Income) loss from equity method investments                                      (1,105)us-gaap_IncomeLossFromEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (4,405)us-gaap_IncomeLossFromEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (10,001)us-gaap_IncomeLossFromEquityMethodInvestments
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(Gain) loss on sale of equity method investment                                      593us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
       
Impairment of equity method investment                                             10,680us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(Income) loss from consolidated entities                                               
Impairment of investments                                               
(Gain) loss on derivative instruments                                                 
Loss on debt extinguishment                                                
Other income                                      (1)us-gaap_OtherNonoperatingIncome
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
         
Other expense, net                                      511us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  4,405us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  20,681us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Income (loss) from continuing operations before income taxes                               430us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    (9,305)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (5,090)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (20,694)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Provision (benefit) for income taxes                                                  
Income (loss) from continuing operations                                      (9,305)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (5,090)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (20,694)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Discontinued operations:                                              
Income (loss) from discontinued operations , net                                                  
Gain (loss) on disposal of discontinued operations, net                                                  
Net income (loss)                               430us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (9,305)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(9,305)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(5,090)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(5,090)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(20,694)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(20,694)us-gaap_ProfitLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Less: Net income (loss) attributable to noncontrolling interest                               208us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    (4,309)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (321)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (6)us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Net income (loss) attributable to common stockholders                               222us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
    (4,996)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (4,769)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
  (20,688)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Elimination [Member]                                              
Condensed Financial Statements, Captions [Line Items]                                              
Revenues                                                  
Operating expenses:                                              
Cost of operations                                                  
General and administration                                                  
Depreciation and amortization                                                  
Asset impairment charge                                                
Legal settlement                                               
Development project charge                                                
Severance and reorganization costs                                                 
Environmental remediation charge                                                
(Gain) expense from divestiture, acquisition and financing costs                                                 
Change in fair value of acquisition related contingent consideration                                               
Total operating expenses                                                  
Operating income (loss)                                                  
Other expense (income), net:                                              
Interest income                                           32,868us-gaap_InterestIncomeOther
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ConsolidationEliminationsMember
  39,863us-gaap_InterestIncomeOther
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Interest expense                                           (32,868)us-gaap_InterestExpense
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= us-gaap_ConsolidationEliminationsMember
  (39,863)us-gaap_InterestExpense
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= us-gaap_ConsolidationEliminationsMember
(Income) loss from equity method investments                                      (18,811)us-gaap_IncomeLossFromEquityMethodInvestments
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= us-gaap_ConsolidationEliminationsMember
  24,723us-gaap_IncomeLossFromEquityMethodInvestments
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  66,832us-gaap_IncomeLossFromEquityMethodInvestments
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(Gain) loss on sale of equity method investment                                                
Impairment of equity method investment                                               
(Income) loss from consolidated entities                               26,148cwst_IncomeLossFromSubsidiaries
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= us-gaap_ConsolidationEliminationsMember
             
Impairment of investments                                               
(Gain) loss on derivative instruments                                                 
Loss on debt extinguishment                                                
Other income                                                  
Other expense, net                               26,148us-gaap_NonoperatingIncomeExpense
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    18,811us-gaap_NonoperatingIncomeExpense
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  (24,723)us-gaap_NonoperatingIncomeExpense
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  (66,832)us-gaap_NonoperatingIncomeExpense
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Income (loss) from continuing operations before income taxes                               (26,148)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
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    (18,811)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
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  24,723us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
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  66,832us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
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Provision (benefit) for income taxes                                                  
Income (loss) from continuing operations                                      (18,811)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
/ us-gaap_ConsolidationItemsAxis
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  24,723us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
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  66,832us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest
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Discontinued operations:                                              
Income (loss) from discontinued operations , net                                                  
Gain (loss) on disposal of discontinued operations, net                                                  
Net income (loss)                               (26,148)us-gaap_ProfitLoss
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  (18,811)us-gaap_ProfitLoss
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(18,811)us-gaap_ProfitLoss
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24,723us-gaap_ProfitLoss
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24,723us-gaap_ProfitLoss
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66,832us-gaap_ProfitLoss
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66,832us-gaap_ProfitLoss
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Less: Net income (loss) attributable to noncontrolling interest                                                  
Net income (loss) attributable to common stockholders                               $ (26,148)us-gaap_NetIncomeLoss
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    $ (18,811)us-gaap_NetIncomeLoss
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  $ 24,723us-gaap_NetIncomeLoss
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  $ 66,832us-gaap_NetIncomeLoss
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