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Derivative Instruments - Gas hedges (Details) - Natural gas swaps $ in Thousands, MMBTU in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) MMBTU	Dec. 31, 2022 USD ($)
Derivative Instruments
Derivative asset \| $	$ 64,584	$ 131,804
Notional volume of natural gas derivatives (in MMBTUs)	113.1
Three counterparties
Derivative Instruments
Credit collateral posted \| $	$ 16,000
One counterparty
Derivative Instruments
Credit collateral posted \| $		$ 30,400
2023
Derivative Instruments
Notional volume of natural gas derivatives (in MMBTUs)	30.3
2024
Derivative Instruments
Notional volume of natural gas derivatives (in MMBTUs)	30.4
2025
Derivative Instruments
Notional volume of natural gas derivatives (in MMBTUs)	24.9
2026
Derivative Instruments
Notional volume of natural gas derivatives (in MMBTUs)	19.9
2027
Derivative Instruments
Notional volume of natural gas derivatives (in MMBTUs)	7.6