ACCOUNTS RECEIVABLE SECURITIZATION (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Short-term Debt [Line Items]
Costs associated with receivables facility	$ 18,514,000	$ 1,170,000
Line of Credit | Accounts Receivable Securitization Facility
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 100,000,000
Unused commitment fee (as a percent)	0.60%
Accounts receivable eligible for securitization	$ 40,829,000		$ 37,869,000
Outstanding borrowings	0		0
Letters of credit outstanding	47,735,000		52,536,000
Borrowings and issuance of letters of credit remaining capacity	0		0
Cash collateral	6,906,000		14,667,000
Costs associated with receivables facility	$ 382,000	$ 666,000
Minimum | Line of Credit | Accounts Receivable Securitization Facility
Short-term Debt [Line Items]
Security facility program fee (as a percent)	2.00%
Maximum | Line of Credit | Accounts Receivable Securitization Facility
Short-term Debt [Line Items]
Security facility program fee (as a percent)	2.50%
Restricted Cash | Line of Credit | Accounts Receivable Securitization Facility
Short-term Debt [Line Items]
Cash collateral	$ 6,906,000		$ 14,667,000