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Employee Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Net Periodic Benefit Cost (Income) | $ (1,651) | $ (1,568) | $ (4,952) | $ (4,700)
Pension Benefits (Pension Plan) |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Service Cost | 972 | 925 | 2,915 | 2,774
Interest Cost | 4,297 | 4,109 | 12,891 | 12,327
Expected Return on Assets | (6,380) | (6,479) | (19,139) | (19,436)
Amortization of Prior Service Cost | 0 | 0 | 0 | 0
Amortization of Net Actuarial Loss | 40 | 0 | 119 | 0
Net Periodic Benefit Cost (Income) | (1,071) | (1,445) | (3,214) | (4,335)
Pension Benefits (ESSRP) |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Service Cost | 0 | 18 | 0 | 54
Interest Cost | 474 | 472 | 1,422 | 1,417
Expected Return on Assets | 0 | 0 | 0 | 0
Amortization of Prior Service Cost | 0 | 0 | 0 | 0
Amortization of Net Actuarial Loss | 0 | 0 | 0 | 0
Net Periodic Benefit Cost (Income) | 474 | 490 | 1,422 | 1,471
Postretirement Benefits |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Service Cost | 123 | 152 | 368 | 458
Interest Cost | 399 | 668 | 1,199 | 2,006
Expected Return on Assets | 0 | 0 | 0 | 0
Amortization of Prior Service Cost | (1,576) | (1,433) | (4,727) | (4,300)
Amortization of Net Actuarial Loss | 0 | 0 | 0 | 0
Net Periodic Benefit Cost (Income) | $ (1,054) | $ (613) | $ (3,160) | $ (1,836)

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- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 3A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480535/715-20-45-3A Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-18 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (h)(5) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a)(5) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-6 + Details
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- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 3A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480535/715-20-45-3A Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-18 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (h)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-6 + Details
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