MARKETABLE SECURITIES (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 93,301,000	$ 61,753,000
Unrealized Gains	36,000	1,000
Unrealized Losses	(336,000)	(285,000)
Fair Value	93,001,000	61,469,000
Investments with other than temporary unrealized losses	$ 0
Marketable debt security weighted-average remaining maturity	1 year 5 months
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 44,802,000	32,996,000
Unrealized Gains	13,000	0
Unrealized Losses	(110,000)	(148,000)
Fair Value	44,705,000	32,848,000
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	48,499,000	28,757,000
Unrealized Gains	23,000	1,000
Unrealized Losses	(226,000)	(137,000)
Fair Value	$ 48,296,000	$ 28,621,000

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).

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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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Period between issuance and maturity of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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