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Accumulated Other Comprehensive Loss (Tables) | 9 Months Ended
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Sep. 30, 2021
Accumulated Other Comprehensive Loss [Abstract] |
Schedule of Accumulated Other Comprehensive Loss, Net of Tax | Accumulated other comprehensive loss, net of tax, consisted of the following as of September 30, 2021 and December 31, 2020 (dollars in thousands):
|  | September 30, 2021 |  |  | December 31, 2020 |
Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $3,575 and $3,822, respectively |  | $ | 13,451 |  |  | $ | 14,378 |
Reclassification out of Accumulated Other Comprehensive Income | The following table details the reclassifications out of accumulated other comprehensive loss to net income by component for the three and nine months ended September 30 (dollars in thousands):
|  | Amounts Reclassified from Accumulated Other Comprehensive Loss |
|  | Three months ended September 30, |  |  | Nine months ended September 30, |
Details about Accumulated Other Comprehensive Loss Components (Affected Line Item in Statement of Income) |  | 2021 |  |  | 2020 |  |  | 2021 |  |  | 2020 |
Amortization of defined benefit pension and postretirement benefit items |  |  |  |  |  |  |  |  |  |  |  |
Amortization of net prior service cost (a) |  | $ | (200 | ) |  | $ | (200 | ) |  | $ | (600 | ) |  | $ | (600 | )
Amortization of net loss (a) |  |  | 2,369 |  |  |  | 3,120 |  |  |  | 8,299 |  |  |  | 9,341 |
Adjustment due to effects of regulation (a) |  |  | (1,784 | ) |  |  | (2,642 | ) |  |  | (6,525 | ) |  |  | (7,925 | )
Total before tax (b) |  |  | 385 |  |  |  | 278 |  |  |  | 1,174 |  |  |  | 816 |
Tax expense (b) |  |  | (81 | ) |  |  | (58 | ) |  |  | (247 | ) |  |  | (171 | )
Net of tax (b) |  | $ | 304 |  |  | $ | 220 |  |  | $ | 927 |  |  | $ | 645 |
(a) These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 6 for additional details). (b) Description is also the affected line item on the Condensed Consolidated Statement of Income.

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- Definition Tabular disclosure of information about items reclassified out of accumulated other comprehensive income (loss). + References No definition available. + Details
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- Definition Tabular disclosure of the components of accumulated other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450520&loc=d3e32583-110901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=124509347&loc=SL7669686-108580 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900 + Details
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