Derivative Instruments - Gains (Losses) and Notional Volumes (Details) MWh in Millions, MMBTU in Millions, $ in Millions	12 Months Ended
	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