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STOCK OPTIONS - Schedule of Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016
Number of Shares |  |  |  |
Outstanding at beginning of year (in shares) | 471,442 | 340,377 | 340,377 |
Granted (in shares) | 59,000 | 109,200 |  |
Exercised (in shares) | (2,000) | (7,033) |  |
Forfeited (in shares) | (1,600) | (6,000) |  |
Balance (in shares) | 526,842 | 436,544 | 471,442 | 340,377
Weighted-Average Exercise Price |  |  |  |
Outstanding at beginning of year (in USD per share) | $ 24.98 | $ 23.43 | $ 23.43 |
Granted (in USD per share) | 32.66 | 27.00 |  |
Exercised (in USD per share) | 23.00 | 11.94 |  |
Forfeited (in USD per share) | 23.00 | 23.17 |  |
Balance (in USD per share) | $ 25.85 | $ 24.51 | $ 24.98 | $ 23.43
Weighted-Average Remaining Contractual Life in Years |  |  |  |
Outstanding | 7 years 1 month 21 days | 7 years 7 months 17 days | 7 years 3 months 18 days | 7 years 4 months 2 days
Granted | 9 years 10 months 2 days | 9 years 10 months 24 days |  |
Exercised | 6 years 9 months 18 days | 4 years 8 months 23 days |  |
Forfeited | 6 years 9 months 18 days | 7 years 4 months 17 days |  |
Aggregate Intrinsic Value |  |  |  |
Outstanding | $ 3,740 | $ 3,277 | $ 2,696 | $ 194
Granted | 24 | 548 |  |
Exercised | 20 | 141 |  |
Forfeited | $ 16 | $ 53 |  |
Exercisable |  |  |  |
Outstanding (in shares) | 166,384 | 117,484 |  |
Weighted-average exercise price (in USD per share) | $ 23.95 | $ 24.11 |  |
Weighted-Average Remaining Contractual Life in Years | 5 years 10 months 21 days | 7 years 4 days |  |
Aggregate Intrinsic Value | $ 1,496 | $ 930 |  |

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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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