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Defined Benefit Pension Plan (Details) - gas_distribution_territory	Dec. 31, 2020	Dec. 31, 2019
Number of Defined Pension Plans	1
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%	100.00%
Investment in privately held oil and gas company
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	21.00%	20.00%
Real Estate
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3.00%	3.00%
Fixed Income
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	69.00%	71.00%
Cash
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3.00%	1.00%
Hedge Funds
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	4.00%	5.00%
Minimum | Return Seeking Assets | Pension Plan
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	28.00%
Minimum | Hedge Funds | Pension Plan
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	64.00%
Maximum | 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	36.00%

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No definition available.

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+ References

Reference 1: 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 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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