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STOCK-BASED COMPENSATION AND EMPLOYEE BENEFIT PLANS (Performance Stock Awards) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected forfeiture rate employees 7.00%clh_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRateEmployees    
Expected forfeiture rate, executives and directors 4.00%clh_SharebasedCompensationArrangementbySharebasedPaymentAwardFairValueAssumptionsExpectedForfeitureRateExecutivesandDirectors    
Performance stock awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected forfeiture rate employees 7.00%clh_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRateEmployees
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
   
Expected forfeiture rate, executives and directors 4.00%clh_SharebasedCompensationArrangementbySharebasedPaymentAwardFairValueAssumptionsExpectedForfeitureRateExecutivesandDirectors
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
   
Performance evaluation stock-based compensation 2 years 2 years  
Number of Shares      
Number of shares, unvested at beginning of period 109,861us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
   
Granted 131,953us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
   
Forfeited (97,939)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
   
Number of shares, unvested at end of period 143,875us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
109,861us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
 
Weighted Average Grant-Date Fair Value      
Shares, unvested, weighted average grant date fair value, beginning of period (in dollars per share) $ 54.27us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
   
Granted $ 61.97us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
   
Forfeited $ 54.84us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
   
Shares, unvested, weighted average grant date fair value, end of period (in dollars per share) $ 60.94us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
$ 54.27us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
 
Total unrecognized compensation cost $ 400,000.0us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember
   
Total fair value, vested in period     $ 6,000,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= clh_PerformanceStockAwardsMember