Derivatives and Risk Management - Schedule of Energy Commodity Derivative Volumes (Details) MWh in Thousands, MMBTU in Thousands	12 Months Ended
	Dec. 31, 2020 MWh MMBTU	Dec. 31, 2019 MWh MMBTU
Purchase [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh	1	2
2022 | MWh	0	0
2023 | MWh	0	0
2024 | MWh	0
2025 | MWh	0
Purchase [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU	10,353	9,813
2022 | MMBTU	450	153
2023 | MMBTU	0	225
2024 | MMBTU	0
2025 | MMBTU	0
Purchase [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh	224	442
2022 | MWh	0	0
2023 | MWh	0	0
2024 | MWh	0
2025 | MWh	0
Purchase [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU	65,188	78,803
2022 | MMBTU	25,525	25,523
2023 | MMBTU	4,950	4,725
2024 | MMBTU	0
2025 | MMBTU	0
Sales [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh	17	133
2022 | MWh	0	0
2023 | MWh	0	0
2024 | MWh	0
2025 | MWh	0
Sales [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU	5,448	2,984
2022 | MMBTU	1,360	1,040
2023 | MMBTU	1,360	0
2024 | MMBTU	1,370
2025 | MMBTU	1,115
Sales [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh	451	1,724
2022 | MWh	0	246
2023 | MWh	0	0
2024 | MWh	0
2025 | MWh	0
Sales [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU	39,273	37,848
2022 | MMBTU	12,030	13,108
2023 | MMBTU	900	675
2024 | MMBTU	0
2025 | MMBTU	0