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) |