ACCOUNTS RECEIVABLE SECURITIZATION (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Short-term Debt [Line Items]
Restricted cash	$ 25,862,000	$ 25,862,000		$ 0
Costs associated with receivables facility		2,851,000	$ 0
Line of Credit | Accounts Receivable Securitization Facility
Short-term Debt [Line Items]
Maximum borrowing capacity	100,000,000	$ 100,000,000
Unused commitment fee (as a percent)		0.60%
Accounts receivable eligible for securitization	41,188,000	$ 41,188,000		60,582,000
Outstanding borrowings	0	0		0
Letters of credit outstanding	52,536,000	52,536,000		60,582,000
Borrowings and issuance of letters of credit remaining capacity	0	0		$ 0
Restricted cash	11,348,000	11,348,000
Costs associated with receivables facility	$ 658,000	$ 2,184,000
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%