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MARKETABLE SECURITIES - Amortized cost basis, fair value and net unrealized gains on available-for-sale securities (Details) $ in Thousands | Dec. 31, 2018 USD ($)
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Marketable Securities: |
Amortized Cost Basis | $ 7,674
Fair Value | 7,665
Net Unrealized Losses | (9)
Municipal Obligations |
Marketable Securities: |
Amortized Cost Basis | 1,490
Fair Value | 1,490
Net Unrealized Losses | 0
Corporate Obligations |
Marketable Securities: |
Amortized Cost Basis | 6,184
Fair Value | 6,175
Net Unrealized Losses | $ (9)

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