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Employee Benefit Plans (Tables) | 9 Months Ended
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Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items] |
Components of Net Periodic Benefit Cost | The components of net periodic expense were as follows (in thousands):
| Defined Benefit Pension Plan |  | Supplemental Non-qualified Defined Benefit Plans |  | Non-pension Defined Benefit Postretirement Healthcare Plan |
Three Months Ended September 30, | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |
Service cost | $ | 614 |  | $ | 982 |  | $ | (77 | ) | $ | (271 | ) | $ | 381 |  | $ | 492 |
Interest cost |  | 4,381 |  |  | 2,705 |  |  | 369 |  |  | 209 |  |  | 594 |  |  | 321 |
Expected return on plan assets |  | (4,672 | ) |  | (4,631 | ) |  | - |  |  | - |  |  | (55 | ) |  | (31 | )
Net amortization of prior service costs |  | (17 | ) |  | (17 | ) |  | - |  |  | - |  |  | 10 |  |  | (72 | )
Recognized net actuarial loss |  | 498 |  |  | 1,522 |  |  | 8 |  |  | 69 |  |  | (3 | ) |  | 16 |
Net periodic expense (benefit) | $ | 804 |  | $ | 561 |  | $ | 300 |  | $ | 7 |  | $ | 927 |  | $ | 726 |
| Defined Benefit Pension Plan |  | Supplemental Non-qualified Defined Benefit Plans |  | Non-pension Defined Benefit Postretirement Healthcare Plan |
Nine Months Ended September 30, | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |
Service cost | $ | 1,842 |  | $ | 2,946 |  | $ | 1,607 |  | $ | (2,018 | ) | $ | 1,143 |  | $ | 1,476 |
Interest cost |  | 13,142 |  |  | 8,114 |  |  | 1,107 |  |  | 626 |  |  | 1,783 |  |  | 963 |
Expected return on plan assets |  | (14,016 | ) |  | (13,892 | ) |  | - |  |  | - |  |  | (167 | ) |  | (93 | )
Net amortization of prior service costs |  | (51 | ) |  | (51 | ) |  | - |  |  | - |  |  | 30 |  |  | (217 | )
Recognized net actuarial loss (gain) |  | 1,494 |  |  | 4,568 |  |  | 24 |  |  | 207 |  |  | (9 | ) |  | 48 |
Net periodic expense (benefit) | $ | 2,411 |  | $ | 1,685 |  | $ | 2,738 |  | $ | (1,185 | ) | $ | 2,780 |  | $ | 2,177 |
Schedule of Employer Contribution to Employee Benefit Plans | Contributions made in the first nine months of 2023 and anticipated contributions for 2023 and 2024 are as follows (in thousands):
| Contributions Made |  | Additional Contributions |  | Contributions |
| Nine Months Ended September 30, 2023 |  | Anticipated for 2023 |  | Anticipated for 2024 |
Defined Benefit Pension Plan | $ | - |  | $ | - |  | $ | - |
Non-pension Defined Benefit Postretirement Healthcare Plan | $ | 3,690 |  | $ | 1,230 |  | $ | 4,808 |
Supplemental Non-qualified Defined Benefit and Defined Contribution Plans | $ | 1,673 |  | $ | 558 |  | $ | 2,417 |

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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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