ACCOUNTS RECEIVABLE SECURITIZATION (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Short-term Debt [Line Items]
Costs associated with receivables facility			$ 20,628,000	$ 2,851,000
Line of Credit | Accounts Receivable Securitization Facility
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 100,000,000		$ 100,000,000
Unused commitment fee			0.60%
Accounts receivable eligible for securitization	38,384,000		$ 38,384,000		$ 37,869,000
Outstanding borrowings	0		0		0
Letters of credit outstanding	39,902,000		39,902,000		52,536,000
Borrowings and issuance of letters of credit remaining capacity	0		0		0
Cash collateral	1,518,000		1,518,000		14,667,000
Costs associated with receivables facility	344,000	$ 658,000	$ 1,095,000	$ 2,184,000
Minimum | Line of Credit | Accounts Receivable Securitization Facility
Short-term Debt [Line Items]
Security facility program fee			2.00%
Maximum | Line of Credit | Accounts Receivable Securitization Facility
Short-term Debt [Line Items]
Security facility program fee			2.50%
Restricted Cash | Line of Credit | Accounts Receivable Securitization Facility
Short-term Debt [Line Items]
Cash collateral	$ 1,518,000		$ 1,518,000		$ 14,667,000