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ACCUMULATED OTHER COMPREHENSIVE LOSS - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Gain (Loss) on Sale of Securities, Net |  |  | $ 0 | $ (12)
Other components of net periodic pension and postretirement benefits | $ (408) | $ (333) | (816) | (666)
Income tax expense | 486 | 1,263 | 1,547 | 2,540
Net income | (2,527) | (2,956) | (6,966) | (5,935)
Reclassification out of Accumulated Other Comprehensive Income |  |  |  |
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Net income | 14 | 12 | 27 | 33
Accumulated Net Investment Gain (Loss) Attributable to Parent | Reclassification out of Accumulated Other Comprehensive Income |  |  |  |
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Gain (Loss) on Sale of Securities, Net | 0 | (12) | 0 | (12)
Income tax expense | 0 | 4 | 0 | 4
Net income | 0 | (8) | 0 | (8)
Defined Benefit and Other Benefit Plans | Reclassification out of Accumulated Other Comprehensive Income |  |  |  |
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Income tax expense | (4) | (13) | (9) | (25)
Net income | 14 | 20 | 27 | 41
Prior Service Costs | Reclassification out of Accumulated Other Comprehensive Income |  |  |  |
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Other components of net periodic pension and postretirement benefits | (55) | (55) | (110) | (110)
Actuarial Losses | Reclassification out of Accumulated Other Comprehensive Income |  |  |  |
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Other components of net periodic pension and postretirement benefits | $ 73 | $ 88 | $ 146 | $ 176

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