FINANCIAL INSTRUMENTS - Fair Value of Marketable Securities (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		$ 24,947,000
Gross Unrealized Gains		1,000
Gross Unrealized Losses		(1,000)
Fair Value	$ 0	24,947,000
Treasury discount notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		24,947,000
Gross Unrealized Gains		1,000
Gross Unrealized Losses		(1,000)
Fair Value		$ 24,947,000

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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