LONG-TERM DEBT - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Oct. 30, 2018	Sep. 30, 2018
Debt Instrument [Line Items]
Line of credit, principal payment	$ 28.9	$ 18.7
Senior Secured Credit Facility | Department of the Interior, Assistant Secretary—Indian Affairs, Division of Capital Investment | Financial Guarantee
Debt Instrument [Line Items]
Loan guarantee, by third party				90.00%
Senior Secured Credit Facility | BIA Loan Guaranty Program (Second Guaranteed Credit Facility)
Debt Instrument [Line Items]
Term loan			$ 11.3
Senior Secured Credit Facility | BIA Loan Guaranty Program
Debt Instrument [Line Items]
Term loan	$ 35.0