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The price per share of the conversion feature embedded in the debt instrument.

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Face (par) amount of debt instrument at time of issuance.

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SENIOR CONVERTIBLE NOTES (Details) - USD ($)	3 Months Ended		9 Months Ended
SENIOR CONVERTIBLE NOTES (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Aug. 07, 2018
Debt Instrument [Line Items]
Convertible senior notes payable	$ 94,216,000		$ 94,216,000		$ 93,514,000
Senior Notes \| Senior Unsecured Convertible Notes
Debt Instrument [Line Items]
Convertible debt, amount	25,000,000.0		25,000,000.0			$ 100,000,000.0
Debt interest rate						4.00%
Effective interest rate						6.00%
Unamortized discount	4,700,000		4,700,000		5,900,000	$ 8,200,000
Unamortized debt issuance expense	1,800,000		1,800,000		2,300,000
Convertible debt, carrying amount of equity component	7,900,000		7,900,000
Accrued interest	700,000		700,000
Convertible senior notes payable	94,200,000		94,200,000		93,500,000
Fair value of debt	80,100,000		80,100,000		$ 94,900,000
Recognized interest expense	$ 1,600,000	$ 1,600,000	$ 4,700,000	$ 4,700,000
Senior Notes \| Senior Unsecured Convertible Notes \| Pro Forma
Debt Instrument [Line Items]
Debt conversion price (in dollars per share)	$ 17.19		$ 17.19