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Employee Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Net Periodic Benefit Cost | $ 1,480 | $ 2,843 | $ 2,959 | $ 5,684
Pension Benefits (Pension Plan) |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Service Cost | 1,644 | 1,865 | 3,288 | 3,731
Interest Cost | 3,086 | 2,915 | 6,172 | 5,830
Expected Return on Assets | (5,921) | (5,589) | (11,842) | (11,179)
Amortization of Prior Service Cost | 0 | 0 | 0 | 0
Amortization of Net Actuarial Loss | 1,967 | 2,729 | 3,933 | 5,457
Net Periodic Benefit Cost | 776 | 1,920 | 1,551 | 3,839
Pension Benefits (ESSRP) |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Service Cost | 49 | 46 | 98 | 93
Interest Cost | 336 | 307 | 671 | 614
Expected Return on Assets | 0 | 0 | 0 | 0
Amortization of Prior Service Cost | 0 | 0 | 0 | 0
Amortization of Net Actuarial Loss | 142 | 156 | 284 | 311
Net Periodic Benefit Cost | 527 | 509 | 1,053 | 1,018
Postretirement Benefits |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Service Cost | 334 | 431 | 669 | 861
Interest Cost | 511 | 473 | 1,021 | 946
Expected Return on Assets | 0 | 0 | 0 | 0
Amortization of Prior Service Cost | (1,434) | (1,434) | (2,867) | (2,867)
Amortization of Net Actuarial Loss | 766 | 944 | 1,532 | 1,887
Net Periodic Benefit Cost | $ 177 | $ 414 | $ 355 | $ 827

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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 -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(5) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=123453770&loc=SL108413299-114919 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4587-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(5) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e2709-114920 + 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 -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4587-114921 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(3) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=123453770&loc=SL108413299-114919 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(3) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e2709-114920 + Details
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