v3.19.1
FAIR VALUE MEASUREMENTS (Details) - Fair Value, Measurements, Recurring [Member] - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Level 1 [Member] | Money Market Funds [Member]    
Fair value of assets $ 3,050 $ 1,767
Level 2 [Member] | Short-term corporate bonds [Member]    
Fair value of assets 101,734 110,385
Level 2 [Member] | Short-term governmental bonds [Member]    
Fair value of assets 5,330 8,295
Level 2 [Member] | Long-term corporate bonds [Member]    
Fair value of assets 57,252 74,256
Level 2 [Member] | Long-term governmental bonds [Member]    
Fair value of assets
Level 3 [Member] | Long-term Earn-out provision [Member]    
Fair value of liabilities $ (1,045) $ (332)