MARKETABLE SECURITIES - Gross unrealized gains (losses) on marketable securities (Details 1) - USD ($) $ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Schedule of Available-for-sale Securities [Line Items] | ||
| Gross unrealized Gains | $ 0 | $ 0 |
| Gross unrealized (Losses) | (58) | (70) |
| Municipal Obligations | ||
| Schedule of Available-for-sale Securities [Line Items] | ||
| Gross unrealized Gains | 0 | 0 |
| Gross unrealized (Losses) | (56) | (70) |
| Corporate Obligations | ||
| Schedule of Available-for-sale Securities [Line Items] | ||
| Gross unrealized Gains | 0 | 0 |
| Gross unrealized (Losses) | $ (2) | $ 0 |