DEBT - ECP Loans (Narrative) (Details) $ in Millions	May 28, 2020 USD ($)
Debt Instrument [Line Items]
Line of credit facility description	(i) a Term Loan Credit Agreement (the “ECP NewCo Term Loan Credit Agreement”), with SMP TopCo, LLC, a Delaware limited liability company and affiliate of ECP (“ECP NewCo”), as lender and administrative agent, and Mizuho Bank (USA) (“Mizuho”), as collateral agent, in a principal amount of $28.2 million (the “ECP NewCo Loan”), and (ii) a Term Loan Credit Agreement (the “ECP Holdings Term Loan Credit Agreement” and together with the ECP NewCo Term Loan Credit Agreement, the “ECP Term Loan Credit Agreements”), with ECP Holdings, as lender, and ECP NewCo, as administrative agent and Mizuho, as collateral agent, in a principal amount of $6.8 million (the “ECP Holdings Loan” and together with the ECP NewCo Loan, the “ECP Loans”). The ECP Loans were set to mature on March 31, 2021 and bore interest at a rate of 8.00% per annum, with the interest payment due at maturity of the ECP Loans. With borrowings under the Partnership’s Revolving Credit Facility, the Partnership fully repaid all amounts outstanding under the ECP Loans ($35 million of principal and $0.6 million of accrued interest) on August 7, 2020.
ECP NewCo Term Loan Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument principal amount	$ 28.2
ECP Term Loan Credit Agreements [Member]
Debt Instrument [Line Items]
Debt instrument principal amount	$ 6.8
Maturity date	Mar. 31, 2021
Stated interest rate	8.00%
Repayments of loans	$ 35.0
Accrued interest on loan	$ 0.6