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Components of Net Periodic Benefit Cost (Tables) | 6 Months Ended
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Jun. 30, 2023
Components of Net Periodic Benefit Cost |
Schedule of Net Periodic Benefit Costs | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Three Months Ended June 30, | ​ | Six Months Ended June 30,
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | Post-Retirement | ​ | ​ | ​ | ​ | ​ | ​ | ​ | Post-Retirement
​ | ​ | Pension Benefits | ​ | Health Benefits | ​ | Pension Benefits | ​ | Health Benefits
(Dollar amounts in thousands) |  | 2023 |  | 2022 | ​ | 2023 |  | 2022 | ​ | 2023 |  | 2022 | ​ | 2023 |  | 2022
Service cost | ​ | $ | 157 | ​ | $ | 298 | ​ | $ | 5 | ​ | $ | 9 | ​ | $ | 314 | ​ | $ | 595 | ​ | $ | 10 | ​ | $ | 17
Interest cost | ​ |  | 956 | ​ |  | 707 | ​ |  | 39 | ​ |  | 27 | ​ |  | 1,912 | ​ |  | 1,413 | ​ |  | 77 | ​ |  | 55
Expected return on plan assets | ​ |  | (969) | ​ |  | (1,228) | ​ |  | — | ​ |  | — | ​ |  | (1,939) | ​ |  | (2,455) | ​ |  | — | ​ |  | —
Net amortization of prior service cost | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | — | ​ |  | —
Net amortization of net (gain) loss | ​ | ​ | 188 | ​ | ​ | 314 | ​ | ​ | (13) | ​ | ​ | — | ​ | ​ | 376 | ​ | ​ | 629 | ​ | ​ | (26) | ​ | ​ | —
Net Periodic Benefit Cost | ​ | $ | 332 | ​ | $ | 91 | ​ | $ | 31 | ​ | $ | 36 | ​ | $ | 663 | ​ | $ | 182 | ​ | $ | 61 | ​ | $ | 72

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- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 715 -SubTopic 20 -Subparagraph (h) -Name Accounting Standards Codification -Paragraph 1 -Section 50 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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