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Employee Benefit Plans: Defined Benefit Pension Plan (Details) - PensionPlan	Dec. 31, 2023	Dec. 31, 2022
Number of Defined Pension Plans	1
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%	100.00%
Return Seeking Assets
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	24.00%	26.00%
Liability-hedging Assets
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	76.00%	74.00%
Investment in privately held oil and gas company | Return Seeking Assets
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	14.00%	14.00%
Real Estate | Return Seeking Assets
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	5.00%	7.00%
Fixed Income | Return Seeking Assets
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.00%	2.00%
Fixed Income | Liability-hedging Assets
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	74.00%	72.00%
Hedge Funds | Return Seeking Assets
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3.00%	3.00%
Cash | Liability-hedging Assets
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.00%	2.00%
Minimum | Return Seeking Assets | Pension Plan
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	20.00%
Minimum | Hedge Funds | Pension Plan
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	72.00%
Maximum | Return Seeking Assets | Pension Plan
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	28.00%
Maximum | Hedge Funds | Pension Plan
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	80.00%

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Number of Defined Pension Plans

+ References

No definition available.

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

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