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Employee Benefits - Assumptions (Details) | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Pension Plan | Benefit obligation assumptions |  |  |  |
Weighted average assumptions - benefit obligations |  |  |  |
Discount rate |  | 5.19% | 5.49% | 2.96%
Rate of compensation increase |  | 4.00% | 4.00% |
Interest credit rate |  | 4.84% | 4.61% |
Pension Plan | Net periodic benefit cost assumptions |  |  |  |
Weighted average assumptions - net periodic benefit cost |  |  |  |
Discount rate |  | 5.49% | 3.18% | 2.71%
Expected return on plan assets |  | 6.62% | 6.88% | 6.88%
Rate of compensation increase |  | 4.00% | 4.00% | 4.00%
Interest credit rate |  | 4.62% | 3.78% | 3.71%
Pension Plan | Net periodic benefit cost assumptions | Subsequent event |  |  |  |
Weighted average assumptions - net periodic benefit cost |  |  |  |
Expected return on plan assets | 6.62% |  |  |
OPEB Plan | Benefit obligation assumptions |  |  |  |
Weighted average assumptions - benefit obligations |  |  |  |
Discount rate |  | 5.16% | 5.50% | 2.92%
OPEB Plan | Benefit obligation assumptions | Pre 65 |  |  |  |
Medical cost trend rates |  |  |  |
Assumed medical cost trend rate |  | 6.25% | 6.50% |
Ultimate trend rate |  | 5.00% | 5.00% |
Year ultimate trend rate is reached |  | 2031 | 2031 |
OPEB Plan | Benefit obligation assumptions | Post 65 |  |  |  |
Medical cost trend rates |  |  |  |
Assumed medical cost trend rate |  | 6.39% | 6.00% |
Ultimate trend rate |  | 5.00% | 5.00% |
Year ultimate trend rate is reached |  | 2030 | 2031 |
OPEB Plan | Net periodic benefit cost assumptions |  |  |  |
Weighted average assumptions - net periodic benefit cost |  |  |  |
Discount rate |  | 5.50% | 2.92% | 2.66%
Expected return on plan assets |  | 6.50% | 7.00% | 7.00%
OPEB Plan | Net periodic benefit cost assumptions | Subsequent event |  |  |  |
Weighted average assumptions - net periodic benefit cost |  |  |  |
Expected return on plan assets | 6.50% |  |  |
OPEB Plan | Net periodic benefit cost assumptions | Pre 65 |  |  |  |
Medical cost trend rates |  |  |  |
Assumed medical cost trend rate |  | 6.50% | 5.70% | 5.85%
Ultimate trend rate |  | 5.00% | 5.00% | 5.00%
Year ultimate trend rate is reached |  | 2031 | 2028 | 2028
OPEB Plan | Net periodic benefit cost assumptions | Post 65 |  |  |  |
Medical cost trend rates |  |  |  |
Assumed medical cost trend rate |  | 6.00% | 5.67% | 5.80%
Ultimate trend rate |  | 5.00% | 5.00% | 5.00%
Year ultimate trend rate is reached |  | 2031 | 2028 | 2028

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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation 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 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 increase of compensation, used to determine benefit obligation 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 1 -Subparagraph (k)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted-average interest crediting rate used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(4) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + 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 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 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-8 Reference 2: 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 1 -Subparagraph (k)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (l) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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