MARKETABLE SECURITIES (Details) - USD ($) |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Fair Value [Member] | ||
| Certificates of deposit | $ 3,541,000 | $ 8,959,000 |
| Fixed income mutual funds | 11,335,000 | 7,879,000 |
| Corporate bonds and notes | 4,490,000 | 8,892,000 |
| Total marketable securities | 19,366,000 | 25,730,000 |
| Cost Basis [Member] | ||
| Certificates of deposit | 3,534,000 | 8,953,000 |
| Fixed income mutual funds | 11,255,000 | 7,878,000 |
| Corporate bonds and notes | 4,500,000 | 8,813,000 |
| Total marketable securities | 19,289,000 | 25,644,000 |
| Gross Unrealized Gains [Member] | ||
| Certificates of deposit | 7,000 | 6,000 |
| Fixed income mutual funds | 80,000 | 1,000 |
| Corporate bonds and notes | 18,000 | 112,000 |
| Total marketable securities | 105,000 | 119,000 |
| Gross Unrealized Losses [Member] | ||
| Certificates of deposit | 0 | 0 |
| Fixed income mutual funds | 0 | 0 |
| Corporate bonds and notes | (28,000) | (33,000) |
| Total marketable securities | $ (28,000) | $ (33,000) |