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Accumulated Other Comprehensive Loss Accumulated Other Comprehensive Loss (Tables) | 3 Months Ended
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Mar. 31, 2019
Accumulated Other Comprehensive Loss [Abstract] |
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] | Accumulated other comprehensive loss, net of tax, consisted of the following as of March 31, 2019 and December 31, 2018 (dollars in thousands):
| March 31, |  | December 31,
| 2019 |  | 2018
Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $2,048 and $2,091, respectively | $ | 7,706 |  |  | $ | 7,866 |
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] | The following table details the reclassifications out of accumulated other comprehensive loss to net income by component for the three months ended March 31 (dollars in thousands).
|  | Amounts Reclassified from Accumulated Other Comprehensive Loss |  |
Details about Accumulated Other Comprehensive Loss Components |  | 2019 |  | 2018 |  | Affected Line Item in Statement of Income
Amortization of defined benefit pension items |  |  |  |  |
Amortization of net prior service cost |  | $ | (200 | ) |  | $ | (228 | ) |  | (a)
Amortization of net loss |  | 3,661 |  |  | 2,995 |  |  | (a)
Adjustment due to effects of regulation |  | (3,258 | ) |  | (2,508 | ) |  | (a)
|  | 203 |  |  | 259 |  |  | Total before tax
|  | (43 | ) |  | (55 | ) |  | Tax expense
|  | $ | 160 |  |  | $ | 204 |  |  | Net of tax
(a) | These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 7 for additional details).

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- Definition Accumulated Other Comprehensive Loss [Abstract] + References No definition available. + Details
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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://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=114867106&loc=SL7669686-108580 + Details
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