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Derivatives, Hedging Programs and Other Financial Instruments, Narrative (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Collateral posted for net derivatives	$ 0							$ 0
Maturity period of short-term investments	12 months
Customer Deposits, Current	$ 300,000							200,000
Designated as Hedging Instrument \| Purchase
Derivative [Line Items]
Derivative net liability	$ 10,900,000							$ 12,600,000
Scenario, Forecast \| Natural Gas
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage		75.00%	80.00%	80.00%	66.00%	66.00%	68.00%
Scenario, Forecast \| Electricity
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage					36.00%	55.00%	54.00%