DEBT / INTEREST EXPENSE - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Debt Instrument
Debt issuance costs	$ (76)		$ (424)
Total debt	895,022		862,565
Less: current debt	(895,022)		(180,566)
Long-term debt	0		681,999
Revolving Credit Facility
Debt Instrument
Long-term debt, gross	30,000		0
FILO Term Loan \| Term Loan \| FILO Asset-based Term Loan Facility
Debt Instrument
Long-term debt, gross	273,898		266,814
Debt discount	1,100		8,200
Convertible Senior Notes \| Notes
Debt Instrument
Long-term debt, gross	156,427		154,675
Debt discount	314		524
Unamortized conversion feature	2,356	$ 3,900	3,898
Tranche B-2 \| Term Loan Facility \| Amended Term Loan Facility Due March 2021
Debt Instrument
Long-term debt, gross	434,773		441,500
Debt discount	$ 2,000		$ 7,000

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount of a favorable spread to a debt holder between the amount of debt being converted and the value of the securities received upon conversion. This is an embedded conversion feature of convertible debt issued that is in-the-money at the commitment date.

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Amount, after accumulated amortization, of debt discount.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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