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Employee Postretirement Benefits - Reconciliation of Changes in Fair Value of Plan Assets and Plan's Benefit Obligations (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Change in Fair Value of Plan Assets: |  |  |
Fair Value of Plan Assets, beginning balance | $ 387,212 |  |
Fair Value of Plan Assets, ending balance | 313,798 | $ 387,212 |
Pension Benefits (Pension Plan) |  |  |
Change in Fair Value of Plan Assets: |  |  |
Fair Value of Plan Assets, beginning balance | 387,212 | 360,678 |
Actual Return on Plan Assets | (76,485) | 32,816 |
Company Contributions | 20,000 | 10,000 |
Benefit Payments | (16,930) | (16,282) |
Participant Premium Payments | 0 | 0 |
Fair Value of Plan Assets, ending balance | 313,797 | 387,212 | $ 360,678
Change in Benefit Obligation: |  |  |
Projected Benefit Obligation, beginning balance | 416,697 | 428,396 |
Service Cost | 6,576 | 7,462 | 6,621
Interest Cost | 12,344 | 11,660 | 13,053
Benefit Payments | (16,930) | (16,282) |
Participant Premium Payments | 0 | 0 |
Plan Amendments | 0 | 0 |
Actuarial Loss | (110,632) | (14,539) |
Projected Benefit Obligation, ending balance | 308,055 | 416,697 | 428,396
Funded Status | 5,742 | (29,485) |
Amounts Recognized in Consolidated Balance Sheet at December 31: |  |  |
Noncurrent Assets | 5,742 | 0 |
Current Liabilities | 0 | 0 |
Noncurrent Liabilities and Deferred Credits | 0 | (29,485) |
Net Asset (Liability) | 5,742 | (29,485) |
Pension Benefits (ESSRP) |  |  |
Change in Fair Value of Plan Assets: |  |  |
Fair Value of Plan Assets, beginning balance | 0 | 0 |
Actual Return on Plan Assets | 0 | 0 |
Company Contributions | 2,205 | 1,562 |
Benefit Payments | (2,205) | (1,562) |
Participant Premium Payments | 0 | 0 |
Fair Value of Plan Assets, ending balance | 0 | 0 | 0
Change in Benefit Obligation: |  |  |
Projected Benefit Obligation, beginning balance | 46,840 | 47,894 |
Service Cost | 195 | 187 | 179
Interest Cost | 1,341 | 1,228 | 1,449
Benefit Payments | (2,205) | (1,562) |
Participant Premium Payments | 0 | 0 |
Plan Amendments | 0 | 0 |
Actuarial Loss | (10,547) | (907) |
Projected Benefit Obligation, ending balance | 35,624 | 46,840 | 47,894
Funded Status | (35,624) | (46,840) |
Amounts Recognized in Consolidated Balance Sheet at December 31: |  |  |
Noncurrent Assets | 0 | 0 |
Current Liabilities | (2,414) | (2,352) |
Noncurrent Liabilities and Deferred Credits | (33,210) | (44,488) |
Net Asset (Liability) | (35,624) | (46,840) |
Postretirement Benefits |  |  |
Change in Fair Value of Plan Assets: |  |  |
Fair Value of Plan Assets, beginning balance | 0 | 0 |
Actual Return on Plan Assets | 0 | 0 |
Company Contributions | 2,294 | 2,695 |
Benefit Payments | (8,173) | (8,385) |
Participant Premium Payments | 5,879 | 5,690 |
Fair Value of Plan Assets, ending balance | 0 | 0 | 0
Change in Benefit Obligation: |  |  |
Projected Benefit Obligation, beginning balance | 69,311 | 70,185 |
Service Cost | 1,338 | 1,722 | 1,847
Interest Cost | 2,041 | 1,891 | 2,393
Benefit Payments | (8,172) | (8,385) |
Participant Premium Payments | 5,879 | 5,690 |
Plan Amendments | 0 | 0 |
Actuarial Loss | (20,450) | (1,792) |
Projected Benefit Obligation, ending balance | 49,947 | 69,311 | $ 70,185
Funded Status | (49,947) | (69,311) |
Amounts Recognized in Consolidated Balance Sheet at December 31: |  |  |
Noncurrent Assets | 0 | 0 |
Current Liabilities | (2,970) | (2,830) |
Noncurrent Liabilities and Deferred Credits | (46,977) | (66,481) |
Net Asset (Liability) | $ (49,947) | $ (69,311) |

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- Definition Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: 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 + Details
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- Definition Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(4) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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- Definition Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(6) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 50 -Paragraph 4 -URI https://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964 + Details
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