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Derivatives, Hedging Programs and Other Financial Instruments, Narrative (Details) - USD ($) | 3 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Mar. 31, 2020 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Derivative [Line Items] |  |  |  |  |  |  |
Collateral posted for net derivatives | $ 0 |  |  |  |  |  | $ 0
Cash collateral posted from customers | $ 2,100,000 |  |  |  |  |  | 200,000
Maturity period of short-term investments | 12 months |  |  |  |  |  |
Designated as Hedging Instrument | Purchase |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Derivative net liability | $ 29,200,000 |  |  |  |  |  | $ 7,200,000
Scenario, Forecast | Natural Gas |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  | 75.00% | 80.00% | 80.00% | 76.00% | 75.00% |
Scenario, Forecast | Electricity |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  |  |  | 46.00% | 55.00% | 55.00% |

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