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MARKETABLE SECURITIES - Narrative (Details) | 9 Months Ended |
--- | --- | ---
Sep. 30, 2017 USD ($) security position | Sep. 30, 2016 security | Dec. 31, 2016 USD ($) position
Schedule of Available-for-sale Securities [Line Items] |  |  |
Carrying value | $ 179,081,000 |  | $ 189,371,000
Unrealized losses | 1,085,000 |  | 4,700,000
Other than temporary impairment losses on debt securities related to credit losses | $ 0 |  | $ 0
Number of investment positions in an unrealized loss position | position | 104 |  | 177
Fair value of securities pledged as collateral | $ 221,777,000 |  | $ 259,499,000
Number of held-to-maturity securities sold | security | 3 | 3 |
Non-Agency Collateralized Mortgage Obligations |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Carrying value | $ 1,470,000 |  |
Unrealized losses | $ 503,000 |  |

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