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Derivative Instruments (Details)	6 Months Ended
	Jun. 30, 2020
Electricity (in MWH) [Member] | Third quarter 2020 [Member]
Derivative [Line Items]
Volume	69,200
Electricity (in MWH) [Member] | Fourth quarter 2020 [Member]
Derivative [Line Items]
Volume	134,859
Electricity (in MWH) [Member] | First quarter 2021 [Member]
Derivative [Line Items]
Volume
Electricity (in MWH) [Member] | Second quarter 2021 [Member]
Derivative [Line Items]
Volume
Electricity (in MWH) [Member] | Third quarter 2021 [Member]
Derivative [Line Items]
Volume
Electricity (in MWH) [Member] | Fourth quarter 2021 [Member]
Derivative [Line Items]
Volume
Electricity (in MWH) [Member] | First quarter 2022 [Member]
Derivative [Line Items]
Volume
Electricity (in MWH) [Member] | Second quarter 2022 [Member]
Derivative [Line Items]
Volume
Electricity (in MWH) [Member] | Third quarter 2022 [Member]
Derivative [Line Items]
Volume
Electricity (in MWH) [Member] | Fourth quarter 2022 [Member]
Derivative [Line Items]
Volume
Electricity (in MWH) [Member] | First quarter 2023
Derivative [Line Items]
Volume
Electricity (in MWH) [Member] | Second quarter 2023
Derivative [Line Items]
Volume
Natural gas (in Dth) [Member] | Third quarter 2020 [Member]
Derivative [Line Items]
Volume	72,961
Natural gas (in Dth) [Member] | Fourth quarter 2020 [Member]
Derivative [Line Items]
Volume	122,651
Natural gas (in Dth) [Member] | First quarter 2021 [Member]
Derivative [Line Items]
Volume	133,750
Natural gas (in Dth) [Member] | Second quarter 2021 [Member]
Derivative [Line Items]
Volume	89,800
Natural gas (in Dth) [Member] | Third quarter 2021 [Member]
Derivative [Line Items]
Volume	67,850
Natural gas (in Dth) [Member] | Fourth quarter 2021 [Member]
Derivative [Line Items]
Volume	68,700
Natural gas (in Dth) [Member] | First quarter 2022 [Member]
Derivative [Line Items]
Volume	67,300
Natural gas (in Dth) [Member] | Second quarter 2022 [Member]
Derivative [Line Items]
Volume	40,000
Natural gas (in Dth) [Member] | Third quarter 2022 [Member]
Derivative [Line Items]
Volume	8,650
Natural gas (in Dth) [Member] | Fourth quarter 2022 [Member]
Derivative [Line Items]
Volume	9,000
Natural gas (in Dth) [Member] | First quarter 2023
Derivative [Line Items]
Volume	8,450
Natural gas (in Dth) [Member] | Second quarter 2023
Derivative [Line Items]
Volume	1,700

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959

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-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
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