Financial and Other Derivative Instruments (Effect of Derivatives Not Designated as Hedging Instruments) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Derivative Instruments, Gain (Loss) [Line Items]
Total	$ (135)	$ 48
Natural gas | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Total	(112)	94
Natural gas | Fuel, purchased power, gas, and other — non-utility
Derivative Instruments, Gain (Loss) [Line Items]
Total	25	(100)
Electricity | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Total	(53)	45
Environmental & Other | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Total	4	9
Foreign currency exchange contracts | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Total	$ 1	$ 0