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ACCUMULATED OTHER COMPREHENSIVE LOSS - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Realized gains on securities available for sale |  |  | $ 0 | $ (12)
Income tax expense | $ 1,802 | $ 1,710 | 3,349 | 4,250
Other components of net periodic pension and postretirement benefits | (408) | (333) | (1,224) | (999)
Net income | (6,930) | (3,654) | (13,896) | (9,589)
Reclassification out of Accumulated Other Comprehensive Income |  |  |  |
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Net income | 13 | 21 | 40 | 54
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] |  |  |  |
Realized gains on securities available for sale | 0 | 0 | 0 | (12)
Income tax expense | 0 | 0 | 0 | 4
Net income | 0 | 0 | 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) | (12) | (13) | (37)
Net income | 13 | 21 | 40 | 62
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) | (165) | (165)
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 | $ 72 | $ 88 | $ 218 | $ 264

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