LONG-TERM DEBT / INTEREST EXPENSE - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Debt Instrument
Other	$ (24)	$ 7	$ (19)	$ 728
Interest expense, net	32,943	16,067	54,716	31,961
Revolving Credit Facility
Debt Instrument
Interest expense (excluding amortization)	0	1,505	316	2,794
Senior Credit Facility
Debt Instrument
Amortization of discount and debt issuance costs	3,540	625	5,295	1,250
Interest expense	30,384	12,318	49,591	23,750
Senior Credit Facility \| Revolving Credit Facility
Debt Instrument
Interest expense (excluding amortization)			370	0
Senior Credit Facility \| Term Loan Facility
Debt Instrument
Interest expense (excluding amortization)			9,741	19,706
Senior Credit Facility \| Asset-backed Securities \| Revolving Credit Facility
Debt Instrument
Interest expense (excluding amortization)	238	0
FILO Asset-based Term Loan Facility \| Asset-backed Securities \| Term Loan
Debt Instrument
Interest expense (excluding amortization)	6,218	0	8,340	0
1.5% Convertible Senior Notes, Due 2020 \| Convertible Senior Notes
Debt Instrument
Interest expense (excluding amortization)	707	1,054	1,414	2,132
Amortization of conversion feature	1,633	2,377	3,243	4,734
Amortization of discount and debt issuance costs	243	311	487	617
Interest expense	2,583	3,742	5,144	7,483
Tranche B-1 \| Senior Credit Facility \| Term Loan Facility
Debt Instrument
Interest expense (excluding amortization)	1,683	10,188
Tranche B-2 \| Senior Credit Facility \| Term Loan Facility
Debt Instrument
Interest expense (excluding amortization)	$ 18,705	$ 0	$ 25,529	$ 0

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Other Interest Income (Expense), Nonoperating, Net

+ References

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Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph 8
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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The net amount of nonoperating interest income (expense).

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