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Derivative Instruments - Gains (Losses) and Notional Volumes (Details) MWh in Millions, MMBTU in Millions, $ in Millions | 12 Months Ended
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Dec. 31, 2023 USD ($) MWh MMBTU | Dec. 31, 2022 USD ($) MWh MMBTU | Dec. 31, 2021 USD ($) MMBTU MWh
Realized gains (losses) on derivatives |  |  |
Gains (losses) | $ (233.2) | $ 311.3 | $ 154.2
Non-Utility Energy Infrastructure |  |  |
Realized gains (losses) on derivatives |  |  |
Realized gains and losses on derivatives income statement location | Operating revenues | Operating revenues | Operating revenues
Public utilities |  |  |
Realized gains (losses) on derivatives |  |  |
Realized gains and losses on derivatives income statement location | Cost of sales | Cost of sales | Cost of sales
Natural gas contracts |  |  |
Realized gains (losses) on derivatives |  |  |
Gains (losses) | $ (259.1) | $ 299.5 | $ 136.5
Notional sales volumes |  |  |
Notional sales volumes | MMBTU | 198.0 | 183.3 | 197.6
FTRs and TCRs |  |  |
Realized gains (losses) on derivatives |  |  |
Gains (losses) | $ 25.9 | $ 11.8 | $ 17.7
Notional sales volumes |  |  |
Notional sales volumes | MWh | 30.2 | 27.2 | 28.2

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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4A + Details
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- Definition Indicates line item in statement of income or comprehensive income that includes gain (loss) from derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4A + Details
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- Definition Nominal energy measure used to calculate payments on a derivative instrument. + References No definition available. + Details
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