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SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Millions | 3 Months Ended
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Jun. 30, 2020 USD ($)
Accounting Policies [Abstract] |
Benefit amount under CARES Act and CEWS | $ 23.4

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- Definition Benefit Under CARES Act And CEWS, Amount + References No definition available. + Details
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Namespace Prefix: | clh_
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Balance Type: | credit
Period Type: | duration

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | na
Period Type: | duration