LONG-TERM DEBT / INTEREST EXPENSE - Convertible Debt: Repurchase (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Repayments of convertible debt		$ 24,708	$ 0	$ 0
Gain (loss) on repurchase of debt instrument		3,214	0	10,996
Notes (net of $3.9 million and $11.5 million conversion feature and $0.5 million and $1.6 million discount) \| Notes (net of $3.9 million and $11.5 million conversion feature and $0.5 million and $1.6 million discount)
Debt Instrument [Line Items]
Debt instrument, repurchased face amount	$ 29,500
Repayments of convertible debt	24,700
Gain (loss) on repurchase of debt instrument	3,200
Convertible, beneficial conversion feature	1,300
Unamortized discount	$ 200	$ 895	$ 974	$ 1,251

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

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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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Face (par) amount of the original debt instrument that was repurchased.

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Amount of gain (loss) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase.

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The cash outflow from the repayment of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

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