Accounting for Derivative Instruments and Hedging Activities - Net Notional Volume Buy/Sell of Open Derivative Transactions (Details) - Long certificate in Millions, bbl in Millions, T in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($) MMBTU MWh certificate T bbl	Dec. 31, 2023 USD ($) MWh MMBTU certificate T bbl
Emissions
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton) | T	1	0
RECs
Volumetric Underlying Derivative Transactions
Derivative, non-monetary notional amount (in shares) | certificate	12	12
Coal
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, mass (ton) | T	11	9
Natural Gas
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MMBTU	759	838
Oil
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount (in barrels) | bbl	1	0
Power
Volumetric Underlying Derivative Transactions
Derivative, nonmonetary notional amount, energy measure (MMBtu/MW/Day) | MWh	206	201
Interest
Volumetric Underlying Derivative Transactions
Derivative, notional amount	$ 1,700	$ 1,000
Foreign Exchange
Volumetric Underlying Derivative Transactions
Derivative, notional amount	433	548
Consumer Financing Program
Volumetric Underlying Derivative Transactions
Derivative, notional amount	$ 1,275	$ 1,116