Accounting for Derivative Instruments and Hedging Activities - Net Notional Volume Buy/Sell of Open Derivative Transactions (Details) certificate in Millions, T in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) MWh MMBTU certificate T	Dec. 31, 2024 USD ($) MWh MMBTU certificate T
Long | Emissions
Derivative [Line Items]
Derivative, nonmonetary notional amount, mass (ton) | T	2	1
Long | Renewables Energy Certificates
Derivative [Line Items]
Derivative, non-monetary notional amount (in shares) | certificate	13	13
Long | Coal
Derivative [Line Items]
Derivative, nonmonetary notional amount, mass (ton) | T	8	10
Long | Power
Derivative [Line Items]
Derivative, nonmonetary notional amount, energy measure in (millions of btu) and (megawatt hours) | MWh	103	91
Long | Interest
Derivative [Line Items]
Derivative, notional amount | $	$ 700	$ 700
Long | Foreign Exchange
Derivative [Line Items]
Derivative, notional amount | $	$ 437	$ 410
Short | Natural Gas
Derivative [Line Items]
Derivative, nonmonetary notional amount, energy measure in (millions of btu) and (megawatt hours) | MMBTU	907	861
Short | Consumer Financing Program
Derivative [Line Items]
Derivative, nonmonetary notional amount, energy measure in (millions of btu) and (megawatt hours) | MWh	1,354	1,219