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BENEFIT PLANS: Defined Benefit Plan, Assumptions Used in Calculations, Net Periodic Benefit Cost (Details) | 12 Months Ended
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Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023
Pension Plan |  |  |
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] |  |  |
Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | 5.70% | 5.10% | 5.45%
Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets | 7.40% | 7.40% | 7.40%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | 4.42% | 4.43% | 4.49%
Senior Management Security Plan |  |  |
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] |  |  |
Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | 5.70% | 5.20% | 5.50%
Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets | 0.00% | 0.00% | 0.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | 4.75% | 4.75% | 4.75%
Postretirement Benefits |  |  |
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] |  |  |
Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate | 5.70% | 5.15% | 5.45%
Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets | 6.00% | 6.00% | 6.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase | 0.00% | 0.00% | 0.00%
Postretirement Benefit, Medical Trend Rate | 6.20% | 7.10% | 6.70%
Postretirement Benefit, Dental Trend Rate | 4.00% | 3.50% | 3.50%

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- Definition Postretirement Benefit, Dental Trend Rate [Line Items] + References No definition available. + Details
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- Definition Postretirement Benefit, Medical Trend Rate + References No definition available. + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (j)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (j)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-8 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (j)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- References No definition available. + Details
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