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MARKETABLE SECURITIES (Tables) | 12 Months Ended
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Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract] |
Schedule of Amortized Cost and Fair Value of Available for Sale and Held to Maturity Securities | The following table summarizes the amortized cost and fair value of securities available for sale and securities held to maturity at December 31, 2017 and 2016 and the corresponding amounts of gross unrealized gains and losses:
December 31, 2017 | Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Estimated Fair Value
Available for sale: |
Corporate bonds | $ | 18,823 |  |  | $ | 64 |  |  | $ | 50 |  |  | $ | 18,837 |
Municipal securities | 7,746 |  |  | — |  |  | 200 |  |  | 7,546 |
Mortgage-backed securities | 92,471 |  |  | — |  |  | 1,793 |  |  | 90,678 |
Collateralized mortgage obligations | 116,809 |  |  | 5 |  |  | 1,503 |  |  | 115,311 |
Total available for sale | $ | 235,849 |  |  | $ | 69 |  |  | $ | 3,546 |  |  | $ | 232,372 |
Held to maturity: |
Municipal securities | $ | 146,496 |  |  | $ | 2,244 |  |  | $ | 218 |  |  | $ | 148,522 |
Mortgage-backed securities | 22,026 |  |  | 199 |  |  | 230 |  |  | 21,995 |
Collateralized mortgage obligations | 6,162 |  |  | 111 |  |  | — |  |  | 6,273 |
Total held to maturity | $ | 174,684 |  |  | $ | 2,554 |  |  | $ | 448 |  |  | $ | 176,790 |
December 31, 2016 | Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Estimated Fair Value
Available for sale: |
Corporate bonds | $ | 25,254 |  |  | $ | 6 |  |  | $ | 377 |  |  | $ | 24,883 |
Municipal securities | 7,841 |  |  | — |  |  | 622 |  |  | 7,219 |
Mortgage-backed securities | 61,298 |  |  | — |  |  | 1,608 |  |  | 59,690 |
Collateralized mortgage obligations | 65,789 |  |  | 10 |  |  | 666 |  |  | 65,133 |
Total available for sale | $ | 160,182 |  |  | $ | 16 |  |  | $ | 3,273 |  |  | $ | 156,925 |
Held to maturity: |
Municipal securities | $ | 149,420 |  |  | $ | 901 |  |  | $ | 3,889 |  |  | $ | 146,432 |
Mortgage-backed securities | 28,450 |  |  | 318 |  |  | 290 |  |  | 28,478 |
Collateralized mortgage obligations | 11,501 |  |  | 265 |  |  | 521 |  |  | 11,245 |
Total held to maturity | $ | 189,371 |  |  | $ | 1,484 |  |  | $ | 4,700 |  |  | $ | 186,155 |
Schedule of Securities with Gross Unrealized Losses | The following table summarizes securities with unrealized losses at December 31, 2017 and 2016, aggregated by major security type and length of time in a continuous unrealized loss position:
| Less Than 12 Months |  | 12 Months or Longer |  | Total
| Gross Unrealized Losses |  | Estimated Fair Value |  | Gross Unrealized Losses |  | Estimated Fair Value |  | Gross Unrealized Losses |  | Estimated Fair Value
December 31, 2017 |  |  |  |  |  |  |  |  |  |  |
Available for sale: |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | $ | (50 | ) |  | $ | 8,019 |  |  | $ | — |  |  | $ | — |  |  | $ | (50 | ) |  | $ | 8,019 |
Municipal securities | — |  |  | — |  |  | (200 | ) |  | 7,546 |  |  | (200 | ) |  | 7,546 |
Mortgage-backed securities | (658 | ) |  | 42,881 |  |  | (1,135 | ) |  | 47,797 |  |  | (1,793 | ) |  | 90,678 |
Collateralized mortgage obligations | (1,091 | ) |  | 93,584 |  |  | (412 | ) |  | 21,258 |  |  | (1,503 | ) |  | 114,842 |
Total available for sale | $ | (1,799 | ) |  | $ | 144,484 |  |  | $ | (1,747 | ) |  | $ | 76,601 |  |  | $ | (3,546 | ) |  | $ | 221,085 |
Held to maturity: |  |  |  |  |  |  |  |  |  |  |
Municipal securities | $ | (37 | ) |  | $ | 9,230 |  |  | $ | (181 | ) |  | $ | 19,961 |  |  | $ | (218 | ) |  | $ | 29,191 |
Mortgage-backed securities | (57 | ) |  | 6,499 |  |  | (173 | ) |  | 9,747 |  |  | (230 | ) |  | 16,246 |
Collateralized mortgage obligations | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Total held to maturity | $ | (94 | ) |  | $ | 15,729 |  |  | $ | (354 | ) |  | $ | 29,708 |  |  | $ | (448 | ) |  | $ | 45,437 |
| Less Than 12 Months |  | 12 Months or Longer |  | Total
| Gross Unrealized Losses |  | Estimated Fair Value |  | Gross Unrealized Losses |  | Estimated Fair Value |  | Gross Unrealized Losses |  | Estimated Fair Value
December 31, 2016 |  |  |  |  |  |  |  |  |  |  |
Available for sale: |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | $ | (377 | ) |  | $ | 22,529 |  |  | $ | — |  |  | $ | — |  |  | $ | (377 | ) |  | $ | 22,529 |
Municipal securities | (622 | ) |  | 7,219 |  |  | — |  |  | — |  |  | (622 | ) |  | 7,219 |
Mortgage-backed securities | (1,047 | ) |  | 44,420 |  |  | (561 | ) |  | 15,270 |  |  | (1,608 | ) |  | 59,690 |
Collateralized mortgage obligations | (437 | ) |  | 55,435 |  |  | (229 | ) |  | 9,049 |  |  | (666 | ) |  | 64,484 |
Total available for sale | $ | (2,483 | ) |  | $ | 129,603 |  |  | $ | (790 | ) |  | $ | 24,319 |  |  | $ | (3,273 | ) |  | $ | 153,922 |
Held to maturity: |  |  |  |  |  |  |  |  |  |  |
Municipal securities | $ | (3,889 | ) |  | $ | 98,943 |  |  | $ | — |  |  | $ | — |  |  | $ | (3,889 | ) |  | $ | 98,943 |
Mortgage-backed securities | (290 | ) |  | 19,983 |  |  | — |  |  | — |  |  | (290 | ) |  | 19,983 |
Collateralized mortgage obligations | — |  |  | — |  |  | (521 | ) |  | 2,350 |  |  | (521 | ) |  | 2,350 |
Total held to maturity | $ | (4,179 | ) |  | $ | 118,926 |  |  | $ | (521 | ) |  | $ | 2,350 |  |  | $ | (4,700 | ) |  | $ | 121,276 |
Schedule of Proceeds from Sales of Securities | The proceeds from sales of securities and the associated gains and losses are listed below:
| 2017 |  | 2016 |  | 2015
Proceeds | $ | 217,111 |  |  | $ | 105,808 |  |  | $ | 140,668 |
Gross gains | 180 |  |  | 243 |  |  | 222 |
Gross losses | (13 | ) |  | (161 | ) |  | (145 | )
Schedule of Sale of Held To Maturity Securities | Sales of securities held to maturity were as follows for the years ended December 31:
| 2017 |  | 2016 |  | 2015
Proceeds from sales | $ | 3,298 |  |  | $ | 1,866 |  |  | $ | — |
Amortized cost | 3,140 |  |  | 1,842 |  |  | — |
Gross realized gains | 158 |  |  | 24 |  |  | — |
Gross realized losses | — |  |  | — |  |  | — |
Tax expense related to securities gains/losses | (44 | ) |  | (7 | ) |  | — |
Investments Classified by Contractual Maturity Date | The contractual maturities at December 31, 2017 of available for sale and held to maturity securities at carrying value and estimated fair value are shown below. The Company invests in mortgage-backed securities and collateralized mortgage obligations that have expected maturities that differ from their contractual maturities. These differences arise because borrowers and/or issuers may have the right to call or prepay their obligation with or without call or prepayment penalties.
| Available for Sale |  | Held to Maturity
| Amortized Cost |  | Estimated Fair Value |  | Amortized Cost |  | Estimated Fair Value
December 31, 2017 |  |  |  |  |  |  |
Due within one year | $ | — |  |  | $ | — |  |  | $ | 2,663 |  |  | $ | 2,665 |
Due after one year through five years | 6,158 |  |  | 6,129 |  |  | 5,769 |  |  | 5,849 |
Due after five years through ten years | 12,665 |  |  | 12,708 |  |  | 42,711 |  |  | 43,903 |
Due after ten years | 7,746 |  |  | 7,546 |  |  | 95,353 |  |  | 96,105 |
Mortgage-backed securities | 92,471 |  |  | 90,678 |  |  | 22,026 |  |  | 21,995 |
Collateralized mortgage obligations | 116,809 |  |  | 115,311 |  |  | 6,162 |  |  | 6,273 |
| $ | 235,849 |  |  | $ | 232,372 |  |  | $ | 174,684 |  |  | $ | 176,790 |

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