FAIR VALUE MEASUREMENTS (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Level 1 [Member] | Money Market Funds [Member]
Fair value of assets	$ 739	$ 1,767
Level 2 [Member] | Short-term corporate bonds [Member]
Fair value of assets	105,266	110,385
Level 2 [Member] | Short-term governmental bonds [Member]
Fair value of assets	4,344	8,295
Level 2 [Member] | Long-term corporate bonds [Member]
Fair value of assets	79,616	74,256
Level 3 [Member] | Long-term Earn-out provision [Member]
Fair value of liabilities	$ (885)	$ (332)