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BUSINESS COMBINATIONS (2014 Acquistions) (Details) (Privately Owned Domestic Company, USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Privately Owned Domestic Company
 
Business Acquisition [Line Items]  
Payments to acquire businesses, gross $ 16.1us-gaap_PaymentsToAcquireBusinessesGross
/ us-gaap_BusinessAcquisitionAxis
= clh_PrivatelyOwnedDomesticCompanyMember