Derivatives and Risk Management - Schedule of Energy Commodity Derivative Volumes (Details) MWh in Thousands, MMBTU in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021 MMBTU MWh	Dec. 31, 2020 MMBTU MWh
Purchase [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh	11	1
2022 | MWh	0	0
2023 | MWh	0	0
2024 | MWh	0	0
2025 | MWh	0	0
Purchase [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU	5,875	10,353
2022 | MMBTU	450	450
2023 | MMBTU	0	0
2024 | MMBTU	0	0
2025 | MMBTU	0	0
Purchase [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh	62	224
2022 | MWh	0	0
2023 | MWh	0	0
2024 | MWh	0	0
2025 | MWh	0	0
Purchase [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU	37,413	65,188
2022 | MMBTU	37,835	25,525
2023 | MMBTU	12,000	4,950
2024 | MMBTU	910	0
2025 | MMBTU	0	0
Sales [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh	47	17
2022 | MWh	0	0
2023 | MWh	0	0
2024 | MWh	0	0
2025 | MWh	0	0
Sales [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU	4,504	5,448
2022 | MMBTU	2,260	1,360
2023 | MMBTU	1,360	1,360
2024 | MMBTU	1,370	1,370
2025 | MMBTU	1,115	1,115
Sales [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh	378	451
2022 | MWh	268	0
2023 | MWh	0	0
2024 | MWh	0	0
2025 | MWh	0	0
Sales [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU	22,943	39,273
2022 | MMBTU	20,820	12,030
2023 | MMBTU	6,160	900
2024 | MMBTU	0	0
2025 | MMBTU	0	0