$CWST
CASELLA WASTE SYSTEMS INC Stock $cwst

$cwst Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-K Financial Statement

#000091117721000009 Filed on February 19, 2021

Income Statement

Concept	2020 Q4	2019 Q4	2019 Q3
Revenue	$200.2M	$193.6M	$198.5M
YoY Change	3.42%	10.81%	14.88%
Cost Of Revenue	$133.3M	$130.9M	$131.3M
YoY Change	1.83%	7.47%	15.03%
Gross Profit	$67.00M	$62.70M	$67.27M
YoY Change	6.86%	18.3%	14.58%
Gross Profit Margin	33.46%	32.38%	33.88%
Selling, General & Admin	$28.20M	$25.40M	$22.50M
YoY Change	11.02%	13.39%	9.76%
% of Gross Profit	42.09%	40.51%	33.45%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$23.50M	$21.70M	$20.94M
YoY Change	8.29%	14.81%	15.04%
% of Gross Profit	35.07%	34.61%	31.13%
Operating Expenses	$51.60M	$47.00M	$47.10M
YoY Change	9.79%	13.8%	21.71%
Operating Profit	$14.21M	$14.60M	$18.49M
YoY Change	-2.71%	-384.24%	-36.0%
Interest Expense	-$5.400M	-$6.200M	$6.235M
YoY Change	-12.9%	-8.82%	-2.94%
% of Operating Profit	-38.01%	-42.45%	33.73%
Other Income/Expense, Net	$500.0K	$500.0K	-$5.921M
YoY Change	0.0%	400.0%	-4.58%
Pretax Income	$9.300M	$8.900M	$12.56M
YoY Change	4.49%	-168.99%	-44.6%
Income Tax	-$53.60M	-$200.0K	$178.0K
% Of Pretax Income	-576.34%	-2.25%	1.42%
Net Earnings	$62.92M	$9.066M	$12.39M
YoY Change	593.99%	-166.29%	-44.46%
Net Earnings / Revenue	31.42%	4.68%	6.24%
Basic Earnings Per Share	$1.25	$0.19	$0.26
Diluted Earnings Per Share	$1.24	$0.19	$0.26
COMMON SHARES
Basic Shares Outstanding	50.44M shares	47.81M shares	47.69M shares
Diluted Shares Outstanding	50.72M shares	48.58M shares	48.36M shares

Balance Sheet

Concept	2020 Q4	2019 Q4	2019 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$154.3M	$3.500M	$5.000M
YoY Change	4308.57%	-12.5%	61.29%
Cash & Equivalents	$154.3M	$3.471M	$5.028M
Short-Term Investments
Other Short-Term Assets	$1.328M	$1.213M	$693.0K
YoY Change	9.48%	-39.59%	-66.95%
Inventory	$7.900M	$7.700M	$7.000M
Prepaid Expenses	$9.289M	$8.994M	$8.423M
Receivables	$74.20M	$80.21M	$89.88M
Other Receivables	$200.0K	$1.300M	$2.800M
Total Short-Term Assets	$247.3M	$102.8M	$113.8M
YoY Change	140.49%	5.89%	11.7%
LONG-TERM ASSETS
Property, Plant & Equipment	$510.5M	$443.8M	$434.1M
YoY Change	15.03%	9.7%	12.09%
Goodwill	$194.9M	$185.8M	$184.3M
YoY Change	4.89%	14.19%	22.03%
Intangibles
YoY Change
Long-Term Investments	$0.00	$0.00	$11.30M
YoY Change			-8.13%
Other Assets	$13.32M	$11.55M	$11.51M
YoY Change	15.32%	3.76%	-7.98%
Total Long-Term Assets	$946.6M	$829.4M	$822.0M
YoY Change	14.14%	30.54%	36.78%
TOTAL ASSETS
Total Short-Term Assets	$247.3M	$102.8M	$113.8M
Total Long-Term Assets	$946.6M	$829.4M	$822.0M
Total Assets	$1.194B	$932.2M	$935.8M
YoY Change	28.08%	27.28%	33.14%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$49.20M	$64.40M	$59.37M
YoY Change	-23.6%	12.41%	5.63%
Accrued Expenses	$65.30M	$57.80M	$59.50M
YoY Change	12.98%	18.44%	23.7%
Deferred Revenue	$2.685M	$2.299M	$2.812M
YoY Change	16.79%	-25.21%	5.16%
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due	$9.200M	$4.300M	$3.600M
YoY Change	113.95%	86.96%	80.0%
Total Short-Term Liabilities	$131.2M	$130.6M	$127.0M
YoY Change	0.47%	17.12%	16.5%
LONG-TERM LIABILITIES
Long-Term Debt	$530.4M	$509.0M	$524.0M
YoY Change	4.2%	-6.09%	1.81%
Other Long-Term Liabilities	$35.98M	$34.76M	$35.40M
YoY Change	3.5%	12.93%	54.8%
Total Long-Term Liabilities	$35.98M	$34.76M	$35.40M
YoY Change	3.5%	12.93%	54.8%
TOTAL LIABILITIES
Total Short-Term Liabilities	$131.2M	$130.6M	$127.0M
Total Long-Term Liabilities	$35.98M	$34.76M	$35.40M
Total Liabilities	$167.2M	$165.4M	$162.4M
YoY Change	1.11%	16.22%	23.14%
SHAREHOLDERS EQUITY
Retained Earnings	-$266.1M	-$357.0M	-$366.1M
YoY Change	-25.47%	-8.14%	-2.38%
Common Stock	$639.2M	$485.3M	$483.0M
YoY Change	31.71%	29.87%	31.25%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$362.1M	$122.8M	$110.8M
YoY Change
Total Liabilities & Shareholders Equity	$1.194B	$932.2M	$935.8M
YoY Change	28.08%	27.28%	33.14%

Cashflow Statement

Concept	2020 Q4	2019 Q4	2019 Q3
OPERATING ACTIVITIES
Net Income	$62.92M	$9.066M	$12.39M
YoY Change	593.99%	-166.29%	-44.46%
Depreciation, Depletion And Amortization	$23.50M	$21.70M	$20.94M
YoY Change	8.29%	14.81%	15.04%
Cash From Operating Activities	$28.00M	$45.30M	$33.20M
YoY Change	-38.19%	46.6%	-20.57%
INVESTING ACTIVITIES
Capital Expenditures	-$30.80M	-$27.20M	-$29.30M
YoY Change	13.24%	27.1%	79.75%
Acquisitions
YoY Change
Other Investing Activities	-$7.000M	-$1.700M	-$45.30M
YoY Change	311.76%	-94.83%	26.89%
Cash From Investing Activities	-$37.80M	-$28.90M	-$74.60M
YoY Change	30.8%	-46.78%	43.46%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	143.0M	-18.00M	43.20M
YoY Change	-894.44%	-174.07%	285.71%
NET CHANGE
Cash From Operating Activities	28.00M	45.30M	33.20M
Cash From Investing Activities	-37.80M	-28.90M	-74.60M
Cash From Financing Activities	143.0M	-18.00M	43.20M
Net Change In Cash	133.2M	-1.600M	1.800M
YoY Change	-8425.0%	-277.78%	80.0%
FREE CASH FLOW
Cash From Operating Activities	$28.00M	$45.30M	$33.20M
Capital Expenditures	-$30.80M	-$27.20M	-$29.30M
Free Cash Flow	$58.80M	$72.50M	$62.50M
YoY Change	-18.9%	38.62%	7.57%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2020	dei	Local Phone Number LocalPhoneNumber	775-0325
CY2020	dei	Entity Central Index Key EntityCentralIndexKey	0000911177
CY2020	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
CY2020	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2020	dei	Amendment Flag AmendmentFlag	false
CY2019	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201613Member
CY2020	dei	Document Type DocumentType	10-K
CY2020	dei	Document Annual Report DocumentAnnualReport	true
CY2020	dei	Document Period End Date DocumentPeriodEndDate	2020-12-31
CY2020	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2020	dei	Document Transition Report DocumentTransitionReport	false
CY2020	dei	Entity File Number EntityFileNumber	000-23211
CY2020	dei	Entity Registrant Name EntityRegistrantName	CASELLA WASTE SYSTEMS, INC.
CY2020	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2020	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	03-0338873
CY2020	dei	Entity Address Address Line1 EntityAddressAddressLine1	25 Greens Hill Lane
CY2020	dei	Entity Address City Or Town EntityAddressCityOrTown	Rutland
CY2020	dei	Entity Address State Or Province EntityAddressStateOrProvince	VT
CY2020	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	05701
CY2020	dei	City Area Code CityAreaCode	(802
CY2020	dei	Security12b Title Security12bTitle	Class A common stock, $0.01 par value per share
CY2020	dei	Trading Symbol TradingSymbol	CWST
CY2020	dei	Security Exchange Name SecurityExchangeName	NASDAQ
CY2020	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2020	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2020	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2020	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2020	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
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CY2020	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
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CY2020	cwst	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Settlements Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossSettlementsBeforeReclassificationAndTax	-3644000	USD
CY2019	cwst	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Settlements Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossSettlementsBeforeReclassificationAndTax	-498000	USD
CY2018	cwst	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Settlements Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossSettlementsBeforeReclassificationAndTax	-361000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	-3679000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	-115000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	-287000	USD
CY2020	cwst	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Change In Fair Value Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossChangeInFairValueBeforeReclassificationAndTax	-7540000	USD
CY2019	cwst	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Change In Fair Value Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossChangeInFairValueBeforeReclassificationAndTax	-4350000	USD
CY2018	cwst	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Change In Fair Value Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossChangeInFairValueBeforeReclassificationAndTax	-1400000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	-7505000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	-4733000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	-1474000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-2029000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	0	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	31653000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	6420000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48793000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	47226000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	42688000	shares
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.87
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.67
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.15
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	49045000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	47966000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	44168000	shares
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.86
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.66
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.15
CY2020	us-gaap	Net Income Loss NetIncomeLoss	91106000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	31653000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	6420000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-5476000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-4733000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-1474000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	85630000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	26920000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	4946000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	-37862000	USD
CY2018	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	1017000	USD
CY2018	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	7622000	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	8445000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	6420000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-1474000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	-15832000	USD
CY2019	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	3996000	USD
CY2019	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	0	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	7223000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	31653000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-4733000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	122753000	USD
CY2020	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	144790000	USD
CY2020	us-gaap	Stock Issued During Period Value Acquisitions StockIssuedDuringPeriodValueAcquisitions	0	USD
CY2020	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	939000	USD
CY2020	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	8219000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	91106000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-5476000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	362142000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	91106000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	31653000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	6420000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	90782000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	79790000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	70508000	USD
CY2018	cwst	Depletion Of Landfill Operating Lease Obligations DepletionOfLandfillOperatingLeaseObligations	9724000	USD
CY2020	us-gaap	Accretion Expense Including Asset Retirement Obligations AccretionExpenseIncludingAssetRetirementObligations	7090000	USD
CY2019	us-gaap	Accretion Expense Including Asset Retirement Obligations AccretionExpenseIncludingAssetRetirementObligations	6976000	USD
CY2018	us-gaap	Accretion Expense Including Asset Retirement Obligations AccretionExpenseIncludingAssetRetirementObligations	5708000	USD
CY2020	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	2169000	USD
CY2019	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	2293000	USD
CY2018	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	2449000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	8219000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	7223000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	8445000	USD
CY2020	us-gaap	Operating Lease Expense OperatingLeaseExpense	8476000	USD
CY2019	us-gaap	Operating Lease Expense OperatingLeaseExpense	9559000	USD
CY2018	us-gaap	Operating Lease Expense OperatingLeaseExpense	0	USD
CY2020	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	-936000	USD
CY2019	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	892000	USD
CY2018	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	492000	USD
CY2020	cwst	Noncash Landfill Closure Charge NoncashLandfillClosureCharge	263000	USD
CY2019	cwst	Noncash Landfill Closure Charge NoncashLandfillClosureCharge	74000	USD
CY2019	us-gaap	Pension Expense Reversal Of Expense Noncash PensionExpenseReversalOfExpenseNoncash	2230000	USD
CY2018	us-gaap	Pension Expense Reversal Of Expense Noncash PensionExpenseReversalOfExpenseNoncash	0	USD
CY2018	cwst	Noncash Landfill Closure Charge NoncashLandfillClosureCharge	16179000	USD
CY2020	cwst	Proceeds From Insurance Settlement Transferred From Operating Activities To Investing Activities ProceedsFromInsuranceSettlementTransferredFromOperatingActivitiesToInvestingActivities	0	USD
CY2019	cwst	Proceeds From Insurance Settlement Transferred From Operating Activities To Investing Activities ProceedsFromInsuranceSettlementTransferredFromOperatingActivitiesToInvestingActivities	0	USD
CY2018	cwst	Proceeds From Insurance Settlement Transferred From Operating Activities To Investing Activities ProceedsFromInsuranceSettlementTransferredFromOperatingActivitiesToInvestingActivities	3506000	USD
CY2020	us-gaap	Noncash Project Abandonment Costs NoncashProjectAbandonmentCosts	0	USD
CY2019	us-gaap	Noncash Project Abandonment Costs NoncashProjectAbandonmentCosts	0	USD
CY2018	us-gaap	Noncash Project Abandonment Costs NoncashProjectAbandonmentCosts	311000	USD
CY2020	cwst	Non Cash Expense From Acquisition Activitiesand Other Items NonCashExpenseFromAcquisitionActivitiesandOtherItems	554000	USD
CY2019	cwst	Non Cash Expense From Acquisition Activitiesand Other Items NonCashExpenseFromAcquisitionActivitiesandOtherItems	65000	USD
CY2018	cwst	Non Cash Expense From Acquisition Activitiesand Other Items NonCashExpenseFromAcquisitionActivitiesandOtherItems	757000	USD
CY2020	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2018	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-7352000	USD
CY2020	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2019	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2018	us-gaap	Impairment Of Investments ImpairmentOfInvestments	1069000	USD
CY2020	us-gaap	Pension Expense Reversal Of Expense Noncash PensionExpenseReversalOfExpenseNoncash	0	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-52288000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-1244000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	1250000	USD
CY2020	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	-5815000	USD
CY2019	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	5464000	USD
CY2018	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	5833000	USD
CY2020	cwst	Increase Decrease In Operating Lease Liabilities IncreaseDecreaseInOperatingLeaseLiabilities	-5386000	USD
CY2019	cwst	Increase Decrease In Operating Lease Liabilities IncreaseDecreaseInOperatingLeaseLiabilities	-5307000	USD
CY2018	cwst	Increase Decrease In Operating Lease Liabilities IncreaseDecreaseInOperatingLeaseLiabilities	0	USD
CY2020	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	-15226000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	6762000	USD
CY2018	us-gaap	Increase Decrease In Accounts Payable IncreaseDecreaseInAccountsPayable	9091000	USD
CY2020	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	1211000	USD
CY2019	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	1669000	USD
CY2018	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	-535000	USD
CY2020	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	-9158000	USD
CY2019	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	-22931000	USD
CY2018	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	-9133000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	139922000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	116829000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	120834000	USD
CY2020	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	32457000	USD
CY2019	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	75379000	USD
CY2018	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	88918000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	108108000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	103165000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	73232000	USD
CY2020	cwst	Payments For Landfill Operating Lease PaymentsForLandfillOperatingLease	0	USD
CY2019	cwst	Payments For Landfill Operating Lease PaymentsForLandfillOperatingLease	0	USD
CY2018	cwst	Payments For Landfill Operating Lease PaymentsForLandfillOperatingLease	7415000	USD
CY2020	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	533000	USD
CY2019	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	750000	USD
CY2018	us-gaap	Proceeds From Sale Of Property Plant And Equipment ProceedsFromSaleOfPropertyPlantAndEquipment	870000	USD
CY2020	us-gaap	Proceeds From Insurance Settlement Investing Activities ProceedsFromInsuranceSettlementInvestingActivities	0	USD
CY2019	us-gaap	Proceeds From Insurance Settlement Investing Activities ProceedsFromInsuranceSettlementInvestingActivities	332000	USD
CY2018	us-gaap	Proceeds From Insurance Settlement Investing Activities ProceedsFromInsuranceSettlementInvestingActivities	992000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-140032000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-177462000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-164197000	USD
CY2020	us-gaap	Proceeds From Issuance Of Long Term Debt And Capital Securities Net ProceedsFromIssuanceOfLongTermDebtAndCapitalSecuritiesNet	157000000	USD
CY2019	us-gaap	Proceeds From Issuance Of Long Term Debt And Capital Securities Net ProceedsFromIssuanceOfLongTermDebtAndCapitalSecuritiesNet	197800000	USD
CY2018	us-gaap	Proceeds From Issuance Of Long Term Debt And Capital Securities Net ProceedsFromIssuanceOfLongTermDebtAndCapitalSecuritiesNet	634700000	USD
CY2020	us-gaap	Repayments Of Long Term Debt And Capital Securities RepaymentsOfLongTermDebtAndCapitalSecurities	149378000	USD
CY2019	us-gaap	Repayments Of Long Term Debt And Capital Securities RepaymentsOfLongTermDebtAndCapitalSecurities	243374000	USD
CY2018	us-gaap	Repayments Of Long Term Debt And Capital Securities RepaymentsOfLongTermDebtAndCapitalSecurities	584223000	USD
CY2020	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	1531000	USD
CY2019	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	749000	USD
CY2018	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	5573000	USD
CY2020	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	100000	USD
CY2019	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	3355000	USD
CY2018	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	471000	USD
CY2020	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	144790000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	100446000	USD
CY2018	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	0	USD
CY2020	cwst	Proceeds From Sale Of Common Stock ProceedsFromSaleOfCommonStock	0	USD
CY2019	cwst	Proceeds From Sale Of Common Stock ProceedsFromSaleOfCommonStock	2619000	USD
CY2018	cwst	Proceeds From Sale Of Common Stock ProceedsFromSaleOfCommonStock	0	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	150981000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	60097000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	45375000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	150871000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-536000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	2012000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	3471000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4007000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	1995000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	154342000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	3471000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4007000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	20117000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	23183000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	23523000	USD
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-1534000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-1631000	USD
CY2018	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	105000	USD
CY2020	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	18069000	USD
CY2019	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	13053000	USD
CY2018	us-gaap	Fair Value Of Assets Acquired FairValueOfAssetsAcquired	7092000	USD
CY2020	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	2	segment
CY2020	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-top:12pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Management’s Estimates and Assumptions</span></div><div style="margin-top:6pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Preparation of our consolidated financial statements in accordance with GAAP requires management to make certain estimates and assumptions. These estimates and assumptions affect the accounting for and recognition and disclosure of assets, liabilities, equity, revenues and expenses. We must make these estimates and assumptions because certain information that we use is dependent on future events, cannot be calculated with a high degree of precision given the available data or simply cannot be readily calculated. In some cases, these estimates are difficult to determine, and we must exercise significant judgment. In preparing our consolidated financial statements, the estimates and assumptions that we consider to be significant and that present the greatest amount of uncertainty relate to our accounting for landfills, environmental remediation liabilities, asset impairments, accounts receivable valuation allowance, self-insurance reserves, deferred taxes and uncertain tax positions, estimates of the fair values of assets acquired and liabilities assumed in any acquisition, contingent liabilities and stock-based compensation. Each of these items is discussed in more detail elsewhere in these notes to consolidated financial statements, as applicable. Actual results may differ materially from the estimates and assumptions that we use in the preparation of our consolidated financial statements.</span></div>
CY2020	us-gaap	Concentration Risk Credit Risk ConcentrationRiskCreditRisk	<div style="margin-top:12pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Concentrations of Credit Risk</span></div><div style="margin-top:6pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Financial instruments that potentially subject us to concentrations of credit risk consist of cash and cash equivalents, restricted investment securities, accounts receivable and derivative instruments. We maintain cash and cash equivalents and restricted investment securities with banks that at times exceed applicable insurance limits. We reduce our exposure to credit risk by maintaining such deposits with high quality financial institutions. Our concentration of credit risk with respect to accounts receivable is limited because of the large number and diversity of customers we serve, thus reducing the credit risk associated with any one customer group. As of December 31, 2020, no single customer or customer group represented greater than 5% of total accounts receivable. We manage credit risk through credit evaluations, credit limits, and monitoring procedures, but generally do not require collateral to support accounts receivable. We reduce our exposure to credit risk associated with derivative instruments by entering into agreements with high quality financial institutions and by evaluating and regularly monitoring their creditworthiness.</span></div>
CY2020	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	413000	USD
CY2019	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	263000	USD
CY2018	us-gaap	Interest Costs Capitalized InterestCostsCapitalized	140000	USD
CY2020	cwst	Closureand Post Closure Costs Incurrence Period ClosureandPostClosureCostsIncurrencePeriod	P30Y
CY2020	cwst	Inflation Rate InflationRate	0.016
CY2020	cwst	Numberof Landfill Operationand Management Agreements Entered Into NumberofLandfillOperationandManagementAgreementsEnteredInto	3	agreement
CY2020	us-gaap	Finite Lived Intangible Asset Useful Life FiniteLivedIntangibleAssetUsefulLife	P10Y
CY2019Q4	us-gaap	Equity Method Investments EquityMethodInvestments	0	USD
CY2020Q4	us-gaap	Equity Method Investments EquityMethodInvestments	0	USD
CY2019Q4	us-gaap	Investments And Other Noncurrent Assets InvestmentsAndOtherNoncurrentAssets	11264000	USD
CY2020Q4	us-gaap	Investments And Other Noncurrent Assets InvestmentsAndOtherNoncurrentAssets	11264000	USD
CY2020	cwst	Maximum Exposure Self Insured MaximumExposureSelfInsured	1250000	USD
CY2020Q4	us-gaap	Self Insurance Reserve SelfInsuranceReserve	16946000	USD
CY2019Q4	us-gaap	Self Insurance Reserve SelfInsuranceReserve	16853000	USD
CY2020Q4	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-54966000	USD
CY2020Q4	us-gaap	Contract With Customer Asset Gross Current ContractWithCustomerAssetGrossCurrent	74162000	USD
CY2019Q4	us-gaap	Contract With Customer Asset Gross Current ContractWithCustomerAssetGrossCurrent	80191000	USD
CY2020Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	2685000	USD
CY2019Q4	us-gaap	Contract With Customer Liability Current ContractWithCustomerLiabilityCurrent	2299000	USD
CY2019	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2018	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2020	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2020	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2019	us-gaap	Impairment Of Investments ImpairmentOfInvestments	0	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	774584000	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	774584000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	743290000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	743290000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	660660000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	660660000	USD
CY2020	us-gaap	Number Of Businesses Acquired NumberOfBusinessesAcquired	10	business
CY2019	us-gaap	Number Of Businesses Acquired NumberOfBusinessesAcquired	9	business
CY2018	us-gaap	Number Of Businesses Acquired NumberOfBusinessesAcquired	9	business
CY2020	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	783177000	USD
CY2019	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	794840000	USD
CY2018	us-gaap	Business Acquisitions Pro Forma Revenue BusinessAcquisitionsProFormaRevenue	774210000	USD
CY2020	cwst	Business Acquisitions Pro Forma Operating Income Loss BusinessAcquisitionsProFormaOperatingIncomeLoss	59467000	USD
CY2019	cwst	Business Acquisitions Pro Forma Operating Income Loss BusinessAcquisitionsProFormaOperatingIncomeLoss	56674000	USD
CY2018	cwst	Business Acquisitions Pro Forma Operating Income Loss BusinessAcquisitionsProFormaOperatingIncomeLoss	49586000	USD
CY2020	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	91064000	USD
CY2019	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	33424000	USD
CY2018	us-gaap	Business Acquisitions Pro Forma Net Income Loss BusinessAcquisitionsProFormaNetIncomeLoss	11708000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48793000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	47226000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	42688000	shares
CY2020	us-gaap	Business Acquisition Pro Forma Earnings Per Share Basic BusinessAcquisitionProFormaEarningsPerShareBasic	1.87
CY2019	us-gaap	Business Acquisition Pro Forma Earnings Per Share Basic BusinessAcquisitionProFormaEarningsPerShareBasic	0.71
CY2018	us-gaap	Business Acquisition Pro Forma Earnings Per Share Basic BusinessAcquisitionProFormaEarningsPerShareBasic	0.27
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	49045000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	47966000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	44168000	shares
CY2020	us-gaap	Business Acquisition Pro Forma Earnings Per Share Diluted BusinessAcquisitionProFormaEarningsPerShareDiluted	1.86
CY2019	us-gaap	Business Acquisition Pro Forma Earnings Per Share Diluted BusinessAcquisitionProFormaEarningsPerShareDiluted	0.70
CY2018	us-gaap	Business Acquisition Pro Forma Earnings Per Share Diluted BusinessAcquisitionProFormaEarningsPerShareDiluted	0.27
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	1468000	USD
CY2018Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	931000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	809000	USD
CY2020	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	1971000	USD
CY2019	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	1360000	USD
CY2018	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	1620000	USD
CY2020	cwst	Accounts Receivable Allowance For Credit Loss Writeoff Recoveries AccountsReceivableAllowanceForCreditLossWriteoffRecoveries	1295000	USD
CY2019	cwst	Accounts Receivable Allowance For Credit Loss Writeoff Recoveries AccountsReceivableAllowanceForCreditLossWriteoffRecoveries	823000	USD
CY2018	cwst	Accounts Receivable Allowance For Credit Loss Writeoff Recoveries AccountsReceivableAllowanceForCreditLossWriteoffRecoveries	1498000	USD
CY2020Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2333000	USD
CY2019Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	1468000	USD
CY2018Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	931000	USD
CY2020Q4	us-gaap	Restricted Cash And Investments Noncurrent RestrictedCashAndInvestmentsNoncurrent	1848000	USD
CY2019Q4	us-gaap	Restricted Cash And Investments Noncurrent RestrictedCashAndInvestmentsNoncurrent	1586000	USD
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	39683000	USD
CY2019Q4	us-gaap	Finance Lease Right Of Use Asset Before Accumulated Amortization FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization	24038000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Before Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization	1411394000	USD
CY2019Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Before Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization	1288699000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization	900882000	USD
CY2019Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization	844874000	USD
CY2020Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	510512000	USD
CY2019Q4	us-gaap	Property Plant And Equipment And Finance Lease Right Of Use Asset After Accumulated Depreciation And Amortization PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	443825000	USD
CY2020	us-gaap	Depreciation Depreciation	54370000	USD
CY2019	us-gaap	Depreciation Depreciation	45060000	USD
CY2018	us-gaap	Depreciation Depreciation	35351000	USD
CY2020	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	3736000	USD
CY2019	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	2122000	USD
CY2020	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	1201000	USD
CY2019	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	767000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	16257000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	17270000	USD
CY2020	us-gaap	Short Term Lease Cost ShortTermLeaseCost	3430000	USD
CY2019	us-gaap	Short Term Lease Cost ShortTermLeaseCost	3878000	USD
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	514000	USD
CY2019	us-gaap	Variable Lease Cost VariableLeaseCost	190000	USD
CY2020	us-gaap	Lease Cost LeaseCost	25138000	USD
CY2019	us-gaap	Lease Cost LeaseCost	24227000	USD
CY2020	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	4940000	USD
CY2019	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	2601000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	13078000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	13840000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	18003000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Finance Lease Liability RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability	9433000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	3845000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	3351000	USD
CY2020Q4	us-gaap	Finance Lease Weighted Average Remaining Lease Term1 FinanceLeaseWeightedAverageRemainingLeaseTerm1	P5Y8M12D
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P10Y7M6D
CY2020Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.042
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.048
CY2020Q4	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	36430000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	20995000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	11702000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Next Twelve Months FinanceLeaseLiabilityPaymentsDueNextTwelveMonths	6286000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	9664000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Two FinanceLeaseLiabilityPaymentsDueYearTwo	6058000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	7435000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Three FinanceLeaseLiabilityPaymentsDueYearThree	5860000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	6638000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Four FinanceLeaseLiabilityPaymentsDueYearFour	5760000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	7512000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	5605000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	47570000	USD
CY2020Q4	us-gaap	Finance Lease Liability Payments Due After Year Five FinanceLeaseLiabilityPaymentsDueAfterYearFive	6861000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	90521000	USD
CY2020Q4	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	4944000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	69526000	USD
CY2020Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	31486000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	185819000	USD
CY2020	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	9082000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	194901000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	162734000	USD
CY2019	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	25704000	USD
CY2019	us-gaap	Goodwill Other Increase Decrease GoodwillOtherIncreaseDecrease	-2619000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	185819000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	105780000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	47456000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	58324000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	97284000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	38563000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	58721000	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	8893000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	7218000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	3316000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	7869000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	7208000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	6969000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	7898000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	8116000	USD
CY2020Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	8768000	USD
CY2018	us-gaap	Interest Expense Debt Excluding Amortization InterestExpenseDebtExcludingAmortization	23431000	USD
CY2020	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	2169000	USD
CY2019Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	9406000	USD
CY2018Q4	cwst	Line Of Credit Facility Additional Borrowing Capacity LineOfCreditFacilityAdditionalBorrowingCapacity	125000000	USD
CY2020	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2019	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	USD
CY2018	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	-7352000	USD
CY2020	us-gaap	Interest Expense Debt Excluding Amortization InterestExpenseDebtExcludingAmortization	20084000	USD
CY2019Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	71927000	USD
CY2020Q4	us-gaap	Finance Lease Weighted Average Discount Rate Percent FinanceLeaseWeightedAverageDiscountRatePercent	0.042
CY2020Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	31486000	USD
CY2019Q4	us-gaap	Finance Lease Liability FinanceLeaseLiability	18364000	USD
CY2020Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	548419000	USD
CY2019Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	522728000	USD
CY2020Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	8768000	USD
CY2019Q4	us-gaap	Deferred Finance Costs Net DeferredFinanceCostsNet	9406000	USD
CY2020Q4	us-gaap	Long Term Debt And Capital Lease Obligations Including Current Maturities LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities	539651000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations Including Current Maturities LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities	513322000	USD
CY2020Q4	us-gaap	Long Term Debt And Capital Lease Obligations Current LongTermDebtAndCapitalLeaseObligationsCurrent	9240000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations Current LongTermDebtAndCapitalLeaseObligationsCurrent	4301000	USD
CY2020Q4	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	530411000	USD
CY2019Q4	us-gaap	Long Term Debt And Capital Lease Obligations LongTermDebtAndCapitalLeaseObligations	509021000	USD
CY2019	us-gaap	Interest Expense Debt Excluding Amortization InterestExpenseDebtExcludingAmortization	22553000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	20264000	USD
CY2019Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	71927000	USD
CY2018Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	73075000	USD
CY2020	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	3840000	USD
CY2019	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	2549000	USD
CY2020	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	4531000	USD
CY2019	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	-1538000	USD
CY2020	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	6436000	USD
CY2019	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	6227000	USD
CY2020	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	4201000	USD
CY2019	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	8386000	USD
CY2020Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	82533000	USD
CY2019	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	2293000	USD
CY2018	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	2449000	USD
CY2020	cwst	Letters Of Credit Fees LettersOfCreditFees	531000	USD
CY2019	cwst	Letters Of Credit Fees LettersOfCreditFees	519000	USD
CY2018	cwst	Letters Of Credit Fees LettersOfCreditFees	554000	USD
CY2020	us-gaap	Interest Costs Capitalized Adjustment InterestCostsCapitalizedAdjustment	413000	USD
CY2019	us-gaap	Interest Costs Capitalized Adjustment InterestCostsCapitalizedAdjustment	263000	USD
CY2018	us-gaap	Interest Costs Capitalized Adjustment InterestCostsCapitalizedAdjustment	140000	USD
CY2020	us-gaap	Interest Expense InterestExpense	22371000	USD
CY2019	us-gaap	Interest Expense InterestExpense	25102000	USD
CY2018	us-gaap	Interest Expense InterestExpense	26294000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	9240000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	16700000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	343443000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	5502000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	30564000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	142970000	USD
CY2020Q4	us-gaap	Debt And Capital Lease Obligations DebtAndCapitalLeaseObligations	548419000	USD
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	P4Y8M12D
CY2019	us-gaap	Goodwill Transfers GoodwillTransfers	-2619000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	4780000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies Undiscounted Due Within One Year AccrualForEnvironmentalLossContingenciesUndiscountedDueWithinOneYear	377000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies Undiscounted Due In Second Year AccrualForEnvironmentalLossContingenciesUndiscountedDueInSecondYear	319000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies Undiscounted Due In Third Year AccrualForEnvironmentalLossContingenciesUndiscountedDueInThirdYear	335000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies Undiscounted Due In Fourth Year AccrualForEnvironmentalLossContingenciesUndiscountedDueInFourthYear	320000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies Undiscounted Due In Fifth Year AccrualForEnvironmentalLossContingenciesUndiscountedDueInFifthYear	345000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies Undiscounted Due After Fifth Year AccrualForEnvironmentalLossContingenciesUndiscountedDueAfterFifthYear	4667000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies Gross AccrualForEnvironmentalLossContingenciesGross	6363000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies Gross AccrualForEnvironmentalLossContingenciesGross	6363000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies Discount AccrualForEnvironmentalLossContingenciesDiscount	1163000	USD
CY2020Q4	us-gaap	Accrual For Environmental Loss Contingencies AccrualForEnvironmentalLossContingencies	5200000	USD
CY2020Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	944000	shares
CY2020Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2019Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	98000	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	9.20
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	0
CY2020	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	8000	shares
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	12.48
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod	0	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice	0
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	90000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	8.91
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	90000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	8.91
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	P4Y8M12D
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	4780000	USD
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	18329000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	8177000	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	10529000	USD
CY2018	us-gaap	Oci Before Reclassifications Before Tax Attributable To Parent OciBeforeReclassificationsBeforeTaxAttributableToParent	-1837000	USD
CY2018	us-gaap	Reclassification From Aoci Current Period Before Tax Attributable To Parent ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent	-363000	USD
CY2019	us-gaap	Oci Before Reclassifications Before Tax Attributable To Parent OciBeforeReclassificationsBeforeTaxAttributableToParent	-5286000	USD
CY2019	us-gaap	Reclassification From Aoci Current Period Before Tax Attributable To Parent ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent	-553000	USD
CY2020	us-gaap	Oci Before Reclassifications Before Tax Attributable To Parent OciBeforeReclassificationsBeforeTaxAttributableToParent	-11184000	USD
CY2020	us-gaap	Reclassification From Aoci Current Period Before Tax Attributable To Parent ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent	-3679000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-2029000	USD
CY2020	us-gaap	Deferred Compensation Arrangement With Individual Requisite Service Period1 DeferredCompensationArrangementWithIndividualRequisiteServicePeriod1	P2Y
CY2020	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	2357000	USD
CY2019	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	1608000	USD
CY2018	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	1319000	USD
CY2019Q4	us-gaap	Multiemployer Plans Withdrawal Obligation MultiemployerPlansWithdrawalObligation	3194000	USD
CY2019	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	3591000	USD
CY2019	us-gaap	Pension Expense PensionExpense	-397000	USD
CY2019	cwst	Multiemployer Plans Withdrawal Obligation Contingent Liability Term MultiemployerPlansWithdrawalObligationContingentLiabilityTerm	P17Y
CY2019Q4	cwst	Multiemployer Plans Withdrawal Obligation Undiscounted MultiemployerPlansWithdrawalObligationUndiscounted	4224000	USD
CY2019Q4	cwst	Multiemployer Plans Complete Withdrawal Estimated Accumulated Benefit Obligation MultiemployerPlansCompleteWithdrawalEstimatedAccumulatedBenefitObligation	18511000	USD
CY2020Q4	us-gaap	Multiemployer Plans Withdrawal Obligation MultiemployerPlansWithdrawalObligation	1757000	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-951000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-951000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-1902000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-35177000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-699000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	1255000	USD
CY2020	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	-36128000	USD
CY2019	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	-1650000	USD
CY2018	us-gaap	Federal Income Tax Expense Benefit Continuing Operations FederalIncomeTaxExpenseBenefitContinuingOperations	-647000	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	435000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	321000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	268000	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-17111000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-545000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-5000	USD
CY2020	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	-16676000	USD
CY2019	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	-224000	USD
CY2018	us-gaap	State And Local Income Tax Expense Benefit Continuing Operations StateAndLocalIncomeTaxExpenseBenefitContinuingOperations	263000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-52804000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-1874000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-384000	USD
CY2020	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-61317000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	6482000	USD
CY2020	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-61317000	USD
CY2019	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-3539000	USD
CY2019Q2	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Goodwill DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill	2385000	USD
CY2019Q2	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-2137000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Alternative Minimum Tax DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax	0	USD
CY2019Q4	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-248000	USD
CY2019	cwst	Deferred Tax Expense Benefit Indefinite Lived Assets DeferredTaxExpenseBenefitIndefiniteLivedAssets	-297000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	8043000	USD
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	6254000	USD
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	1268000	USD
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	1615000	USD
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	1008000	USD
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	-89000	USD
CY2020	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-61317000	USD
CY2019	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-4420000	USD
CY2018	us-gaap	Income Tax Reconciliation Change In Deferred Tax Assets Valuation Allowance IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance	-1613000	USD
CY2020	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	3803000	USD
CY2019	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	0	USD
CY2019	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-627000	USD
CY2018	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-63000	USD
CY2018	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	0	USD
CY2020	cwst	Effective Income Tax Rate Reconciliation Deductible Stock Awards EffectiveIncomeTaxRateReconciliationDeductibleStockAwards	3790000	USD
CY2019	cwst	Effective Income Tax Rate Reconciliation Deductible Stock Awards EffectiveIncomeTaxRateReconciliationDeductibleStockAwards	6004000	USD
CY2018	cwst	Effective Income Tax Rate Reconciliation Deductible Stock Awards EffectiveIncomeTaxRateReconciliationDeductibleStockAwards	2048000	USD
CY2020	cwst	Effective Income Tax Rate Reconciliation Deferred Tax Adjustments Amount EffectiveIncomeTaxRateReconciliationDeferredTaxAdjustmentsAmount	2047000	USD
CY2019	cwst	Effective Income Tax Rate Reconciliation Deferred Tax Adjustments Amount EffectiveIncomeTaxRateReconciliationDeferredTaxAdjustmentsAmount	0	USD
CY2018	cwst	Effective Income Tax Rate Reconciliation Deferred Tax Adjustments Amount EffectiveIncomeTaxRateReconciliationDeferredTaxAdjustmentsAmount	0	USD
CY2020	us-gaap	Income Tax Reconciliation Nondeductible Expense IncomeTaxReconciliationNondeductibleExpense	656000	USD
CY2019	us-gaap	Income Tax Reconciliation Nondeductible Expense IncomeTaxReconciliationNondeductibleExpense	638000	USD
CY2018	us-gaap	Income Tax Reconciliation Nondeductible Expense IncomeTaxReconciliationNondeductibleExpense	633000	USD
CY2020	cwst	Effective Income Tax Rate Reconciliation Nondeductible Expense Officer Compensation EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOfficerCompensation	487000	USD
CY2019	cwst	Effective Income Tax Rate Reconciliation Nondeductible Expense Officer Compensation EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOfficerCompensation	1359000	USD
CY2018	cwst	Effective Income Tax Rate Reconciliation Nondeductible Expense Officer Compensation EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOfficerCompensation	2214000	USD
CY2020	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	130000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	82000	USD
CY2018	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	686000	USD
CY2020	us-gaap	Income Tax Reconciliation Other Reconciling Items IncomeTaxReconciliationOtherReconcilingItems	-124000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-52804000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-1874000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-384000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals	35444000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals	36559000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	34364000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	40556000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Other DeferredTaxAssetsTaxCreditCarryforwardsOther	8044000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Other DeferredTaxAssetsTaxCreditCarryforwardsOther	8422000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	3798000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	1768000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	2824000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	3097000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	0	USD
CY2019Q4	us-gaap	Deferred Tax Assets Property Plant And Equipment DeferredTaxAssetsPropertyPlantAndEquipment	2882000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	2307000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	86781000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	2600000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Alternative Minimum Tax DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax	951000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	96835000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	6482000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	60251000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	5934000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Subject To Expiration DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration	92494000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	67799000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	80299000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	29036000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	18044000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	22910000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	1875000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	0	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	129000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	192000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	20048000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	23102000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	68195000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards General Business DeferredTaxAssetsTaxCreditCarryforwardsGeneralBusiness	6416000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Not Subject To Expiration DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration	46453000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	2000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	1000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	1000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	1000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	1000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	0	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits Interest On Income Taxes Accrued UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued	1000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued	0	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued	1000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	1000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	1000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	2000	USD
CY2020Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	20633000	USD
CY2020	cwst	Expense From Acquisition And Financing Costs And Other Items Acquisition Activities ExpenseFromAcquisitionAndFinancingCostsAndOtherItemsAcquisitionActivities	1862000	USD
CY2019	cwst	Expense From Acquisition And Financing Costs And Other Items Acquisition Activities ExpenseFromAcquisitionAndFinancingCostsAndOtherItemsAcquisitionActivities	2687000	USD
CY2018	cwst	Expense From Acquisition And Financing Costs And Other Items Acquisition Activities ExpenseFromAcquisitionAndFinancingCostsAndOtherItemsAcquisitionActivities	1872000	USD
CY2018	us-gaap	Gain Loss On Contract Termination GainLossOnContractTermination	-2100000	USD
CY2018	us-gaap	Noncash Project Abandonment Costs NoncashProjectAbandonmentCosts	311000	USD
CY2020	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	91106000	USD
CY2019	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	31653000	USD
CY2018	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	6420000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Contingently Issuable WeightedAverageNumberOfSharesContingentlyIssuable	0	shares
CY2019	us-gaap	Weighted Average Number Of Shares Contingently Issuable WeightedAverageNumberOfSharesContingentlyIssuable	36000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Contingently Issuable WeightedAverageNumberOfSharesContingentlyIssuable	103000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	2000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	0	shares
CY2018	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	9000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Issued Basic WeightedAverageNumberOfSharesIssuedBasic	2294000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Issued Basic WeightedAverageNumberOfSharesIssuedBasic	601000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Issued Basic WeightedAverageNumberOfSharesIssuedBasic	338000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48793000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	47226000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	42688000	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	252000	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	740000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	1480000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	49045000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	44168000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	47966000	shares
CY2020	us-gaap	Revenues Revenues	774584000	USD
CY2020	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	2000	shares
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	90782000	USD
CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	2000	shares
CY2020	us-gaap	Related Party Transaction Purchases From Related Party RelatedPartyTransactionPurchasesFromRelatedParty	13046000	USD
CY2019	us-gaap	Related Party Transaction Purchases From Related Party RelatedPartyTransactionPurchasesFromRelatedParty	7574000	USD
CY2018	us-gaap	Related Party Transaction Purchases From Related Party RelatedPartyTransactionPurchasesFromRelatedParty	3442000	USD
CY2020Q4	us-gaap	Accounts Payable Related Parties Current AccountsPayableRelatedPartiesCurrent	1297000	USD
CY2019Q4	us-gaap	Accounts Payable Related Parties Current AccountsPayableRelatedPartiesCurrent	851000	USD
CY1994	cwst	Number Of Leases NumberOfLeases	2	lease
CY2020	us-gaap	Interest Income Expense Nonoperating Net InterestIncomeExpenseNonoperatingNet	-22068000	USD
CY2020	us-gaap	Operating Income Loss OperatingIncomeLoss	59297000	USD
CY2020	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	108108000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	194901000	USD
CY2020Q4	us-gaap	Assets Assets	1193898000	USD
CY2019	us-gaap	Revenues Revenues	743290000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	79790000	USD
CY2019	us-gaap	Operating Income Loss OperatingIncomeLoss	53075000	USD
CY2019	us-gaap	Interest Income Expense Nonoperating Net InterestIncomeExpenseNonoperatingNet	-24735000	USD
CY2019	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	103165000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	185819000	USD
CY2019Q4	us-gaap	Assets Assets	932182000	USD
CY2018	us-gaap	Revenues Revenues	660660000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	70508000	USD
CY2018	us-gaap	Operating Income Loss OperatingIncomeLoss	39733000	USD
CY2018	us-gaap	Interest Income Expense Nonoperating Net InterestIncomeExpenseNonoperatingNet	-26021000	USD
CY2018	us-gaap	Payments To Acquire Productive Assets PaymentsToAcquireProductiveAssets	73232000	USD
CY2018Q4	us-gaap	Goodwill Goodwill	162734000	USD
CY2018Q4	us-gaap	Assets Assets	732410000	USD
CY2020	us-gaap	Revenues Revenues	774584000	USD
CY2020	us-gaap	Concentration Risk Percentage1 ConcentrationRiskPercentage1	1.000
CY2019	us-gaap	Revenues Revenues	743290000	USD
CY2019	us-gaap	Concentration Risk Percentage1 ConcentrationRiskPercentage1	1.000
CY2018	us-gaap	Revenues Revenues	660660000	USD
CY2018	us-gaap	Concentration Risk Percentage1 ConcentrationRiskPercentage1	1.000
CY2020Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	182910000	USD
CY2020Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	188767000	USD
CY2020Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	202667000	USD
CY2020Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	200240000	USD
CY2020Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	7012000	USD
CY2020Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	17444000	USD
CY2020Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	14208000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	959000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	12113000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	15117000	USD
CY2020Q4	us-gaap	Net Income Loss NetIncomeLoss	62917000	USD
CY2020Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48005000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48348000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	48370000	shares
CY2020Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	50436000	shares
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.02
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.25
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.31
CY2020Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.25
CY2020Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48262000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48563000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48619000	shares
CY2020Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	50719000	shares
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.02
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.25
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.31
CY2020Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.24
CY2019Q1	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	163664000	USD
CY2019Q2	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	187459000	USD
CY2019Q3	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	198547000	USD
CY2019Q4	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	193619000	USD
CY2019Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	4442000	USD
CY2019Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	15544000	USD
CY2019Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	18485000	USD
CY2019Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	14604000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	-1714000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	11915000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	12386000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	9066000	USD
CY2019Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	45913000	shares
CY2019Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	47464000	shares
CY2019Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	47690000	shares
CY2019Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	47811000	shares
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.04
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.25
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.26
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.19
CY2019Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	45913000	shares
CY2019Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48221000	shares
CY2019Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48361000	shares
CY2019Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	48583000	shares
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.04
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.25
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.26
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.19
CY2020Q4	us-gaap	Valuation Allowance Deferred Tax Asset Change In Amount ValuationAllowanceDeferredTaxAssetChangeInAmount	-53644000	USD

Files In Submission

Name	View Source	Status
0000911177-21-000009-index-headers.html	Edgar Link	pending
0000911177-21-000009-index.html	Edgar Link	pending
0000911177-21-000009.txt	Edgar Link	pending
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cwst-20201231.htm	Edgar Link	pending
cwst-20201231.xsd	Edgar Link	pending
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$CWST
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2020 Q4 Form 10-K Financial Statement

#000091117721000009 Filed on February 19, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CWST CASELLA WASTE SYSTEMS INC Stock $cwst

2020 Q4 Form 10-K Financial Statement

#000091117721000009 Filed on February 19, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CWST
CASELLA WASTE SYSTEMS INC Stock $cwst