SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Financial Instruments Where Carrying Value and Fair Value Differ (Details) $ in Millions	Dec. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument Carrying Amount Excluding Finance Leases	$ 215.1
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term obligations, fair value	0.0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term obligations, fair value	217.7
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term obligations, fair value	$ 0.0