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ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Amortization of net loss | $ 10,950 | $ 10,648 | $ 21,900 | $ 21,296
Amortization of unrecognized prior service cost | (1,142) | (1,149) | (2,284) | (2,298)
Reclassification adjustment, before tax and regulatory adjustments | 9,808 | 9,499 | 19,616 | 18,998
Regulatory adjustments | (9,537) | (9,289) | (19,074) | (18,579)
Reclassification adjustment, before tax | 271 | 210 | 542 | 419
Reclassification adjustment, Tax | (68) | (81) | (419) | (161)
Reclassification adjustment, net of tax | $ 203 | $ 129 | $ 123 | $ 258

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- Definition Amount, after tax, of reclassification adjustment from accumulated other comprehensive (income) loss for net periodic benefit cost (credit) of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e637-108580 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e689-108580 + Details
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