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Benefit Plans - Change in Project Benefit/Accumulated Benefit Obligations (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Pension and Supplemental Executive Retirement Plans |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation at Beginning of Year | $ 376,153 | $ 417,770 |
Company Service Cost | 8,345 | 10,530 | $ 9,556
Interest Cost | 15,705 | 15,095 | 15,475
Plan Participants' Contributions | 0 | 0 |
Net Actuarial (Gain)/Loss due to Assumption Changes | 43,302 | (36,132) |
Net Actuarial (Gain)/Loss due to Plan Experience | 3,811 | 2,487 |
Benefit Payments from Fund | (30,829) | (32,674) |
Benefit Payments Directly by Company | (3,105) | (908) |
Plan Amendments | (5) | (15) |
Other Adjustment | 0 | 0 |
Settlement (Gain)Loss | (27) | 0 |
Benefit Obligation at End of Year | 413,350 | 376,153 | 417,770
Other Postretirement Benefit Plan |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation at Beginning of Year | 28,085 | 24,716 |
Company Service Cost | 1,345 | 1,160 | 813
Interest Cost | 1,130 | 834 | 706
Plan Participants' Contributions | 382 | 475 |
Net Actuarial (Gain)/Loss due to Assumption Changes | (1,215) | (1,209) |
Net Actuarial (Gain)/Loss due to Plan Experience | (860) | (692) |
Benefit Payments from Fund | (826) | (1,077) |
Benefit Payments Directly by Company | 0 | 0 |
Plan Amendments | 0 | 3,928 |
Other Adjustment | (545) | (50) |
Settlement (Gain)Loss | 0 | 0 |
Benefit Obligation at End of Year | $ 27,496 | $ 28,085 | $ 24,716

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- Definition The net increase or decrease of changes in the value of either the benefit obligation or the plan assets resulting from a change in an actuarial assumption. + References No definition available. + Details
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- Definition The net increase or decrease of changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed. + References No definition available. + Details
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- Definition The amount of payments made directly by the entity for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets. + References No definition available. + Details
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- Definition The amount of payments made from fund for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets. + References No definition available. + Details
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- Definition Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Amount of contributions received by defined benefit plan from participant which increase benefit obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of cost recognized for passage of time related to defined benefit 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 (h)(2) -URI http://asc.fasb.org/extlink&oid=118255775&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 http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details
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- Definition Amount of increase (decrease) in benefit obligation of defined benefit plan from change, classified as other. + References No definition available. + Details
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- Definition Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit 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 (h)(1) -URI http://asc.fasb.org/extlink&oid=118255775&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 http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Amount of (increase) decrease to benefit obligation of defined benefit plan from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Includes, but is not limited to, lump-sum cash payment to participant in exchange for right to receive specified benefits, purchase of nonparticipating annuity contract and change from remeasurement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(10) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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