Summary of Significant Accounting Policies and Other Matters - Reconciliation of Cash, Temporary Investments and Restricted Cash (Details) $ in Millions	Jun. 30, 2024 USD ($) MWh	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 01, 2023 MWh
Cash and Cash Equivalents [Line Items]
Cash and temporary cash investments	$ 1,500	$ 1,189	$ 1,955
Restricted cash	7		1
Total cash, temporary cash investments and restricted cash	$ 1,507		$ 1,956
Electric Energy (MWh)
Cash and Cash Equivalents [Line Items]
Notional amount | MWh	36,200,145
Broken Bow II | Electric Energy (MWh) | Clean Energy Businesses
Cash and Cash Equivalents [Line Items]
Notional amount | MWh	75			75