UNIT-BASED COMPENSATION - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common units reserved for issuance (in shares)	14,856,026	14,856,026
Unit-based compensation expenses	$ 2.1	$ 4.3
Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value			$ 8.6
Unrecognized compensation cost related to unvested phantom units	$ 32.9	$ 32.9
Unrecognized compensation cost related to unvested phantom units, period for recognition		3 years 10 months 13 days

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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