MARKETABLE SECURITIES (Details) - USD ($) |
Mar. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Fair Value [Member] | ||
| Certificates of deposit | $ 2,272,000 | $ 3,541,000 |
| Fixed income mutual funds | 11,361,000 | 11,335,000 |
| Corporate bonds and notes | 3,516,000 | 4,490,000 |
| Total marketable securities | 17,149,000 | 19,366,000 |
| Cost Basis [Member] | ||
| Certificates of deposit | 2,279,000 | 3,534,000 |
| Fixed income mutual funds | 11,377,000 | 11,255,000 |
| Corporate bonds and notes | 3,515,000 | 4,500,000 |
| Total marketable securities | 17,171,000 | 19,289,000 |
| Gross Unrealized Gains [Member] | ||
| Certificates of deposit | 0 | 7,000 |
| Fixed income mutual funds | 0 | 80,000 |
| Corporate bonds and notes | 1,000 | 18,000 |
| Total marketable securities | 1,000 | 105,000 |
| Gross Unrealized Losses [Member] | ||
| Certificates of deposit | (7,000) | 0 |
| Fixed income mutual funds | (16,000) | 0 |
| Corporate bonds and notes | 0 | (28,000) |
| Total marketable securities | $ (23,000) | $ (28,000) |