UNIT-BASED COMPENSATION - Additional Information (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019 USD ($) shares	Sep. 30, 2019 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common units reserved for issuance (in shares) \| shares	15,151,515	15,151,515
Unit-based compensation expenses	$ 2.2	$ 3.0
Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested phantom units	$ 39.1	$ 39.1
Unrecognized compensation cost related to unvested phantom units, period for recognition		2 years 7 months 24 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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