DERIVATIVES - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative liability	$ 21,770	$ 7,483
Derivative liability, current	8,630	5,044
ARM Sales Agreement
Derivative [Line Items]
Derivative liability	3,200
Derivative liability, current	800
Derivative liability, noncurrent	2,400
Fair Value, Recurring
Derivative [Line Items]
Derivative liability	4,441	6,869
Derivative liability, current	8,630	5,044
Derivative liability, noncurrent	13,140	2,439
Embedded Derivative Financial Instruments \| ARM Sales Agreement
Derivative [Line Items]
Derivative liability	20,600
Embedded Derivative Financial Instruments \| ARM Sales Agreement \| Fair Value, Recurring
Derivative [Line Items]
Derivative liability, current	7,500	800
Derivative liability, noncurrent	13,100	$ 2,400
Embedded Derivative Financial Instruments \| ARM Sales Agreement \| Fair Value, Recurring \| Significant Unobservable Inputs (Level 3) \| ARM Sales Agreement
Derivative [Line Items]
Derivative liability	$ (20,600)

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
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-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

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