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MARKETABLE SECURITIES - Narrative (Details) | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2018 USD ($) security position | Sep. 30, 2018 USD ($) security position | Sep. 30, 2017 security | Dec. 31, 2017 USD ($)
Investments, Debt and Equity Securities [Abstract] |  |  |  |
Other than temporary impairment losses on debt securities related to credit losses | $ 0 | $ 0 |  | $ 0
Number of investment positions in an unrealized loss position | position | 203 | 203 |  |
Fair value of securities pledged as collateral | $ 233,559,000 | $ 233,559,000 |  | $ 245,600,000
Number of held-to-maturity securities sold | security | 0 | 0 | 3 |

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- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
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