LONG-TERM DEBT - Receivables Based Credit Facility (Narrative) (Details) - USD ($)			12 Months Ended
	Jan. 31, 2017	Nov. 17, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Additional borrowings under receivables based credit facility			$ 100,000,000	$ 350,000,000	$ 68,010,000
Prepaid amount borrowed under receivables based credit facility			2,100,000	$ 123,849,000	$ 315,682,000
Revolving credit facility | Receivables Based Credit Facility
Line of Credit Facility [Line Items]
Additional borrowings under receivables based credit facility		$ 100,000,000
Borrowings outstanding under receivables based credit facility			330,000,000
Maximum borrowing capacity			$ 535,000,000.0
Borrowing base as a percent of eligible accounts receivable			90.00%
Revolving credit facility | Receivables Based Credit Facility | Subsequent Event
Line of Credit Facility [Line Items]
Borrowings outstanding under receivables based credit facility	$ 305,000,000
Prepaid amount borrowed under receivables based credit facility	$ 25,000,000