Risk Management - Fair Value of Derivative Contracts (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Derivatives, Fair Value [Line Items]
Derivatives Asset	$ 109	$ 248
Derivatives Liability	(416)	(213)
Energy commodity derivative contracts
Derivatives, Fair Value [Line Items]
Derivatives Asset	49	171
Derivatives Liability	(267)	(75)
Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivatives Asset	31	36
Derivatives Liability	(149)	(136)
Foreign currency contracts
Derivatives, Fair Value [Line Items]
Derivatives Asset	29	41
Derivatives Liability		(2)
Derivatives designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivatives Asset	60	169
Derivatives Liability	(287)	(138)
Derivatives designated as hedging instruments \| Energy commodity derivative contracts
Derivatives, Fair Value [Line Items]
Derivatives Asset	0	92
Derivatives Liability	(138)	0
Derivatives designated as hedging instruments \| Energy commodity derivative contracts \| Other current assets
Derivatives, Fair Value [Line Items]
Derivatives Asset	0	56
Derivatives designated as hedging instruments \| Energy commodity derivative contracts \| Deferred charges and other assets
Derivatives, Fair Value [Line Items]
Derivatives Asset	0	36
Derivatives designated as hedging instruments \| Energy commodity derivative contracts \| Other current liabilities
Derivatives, Fair Value [Line Items]
Derivatives Liability	(110)	0
Derivatives designated as hedging instruments \| Energy commodity derivative contracts \| Other long-term liabilities and deferred credits
Derivatives, Fair Value [Line Items]
Derivatives Liability	(28)	0
Derivatives designated as hedging instruments \| Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivatives Asset	31	36
Derivatives Liability	(149)	(136)
Derivatives designated as hedging instruments \| Interest rate contracts \| Other current assets
Derivatives, Fair Value [Line Items]
Derivatives Asset	4	4
Derivatives designated as hedging instruments \| Interest rate contracts \| Deferred charges and other assets
Derivatives, Fair Value [Line Items]
Derivatives Asset	27	32
Derivatives designated as hedging instruments \| Interest rate contracts \| Other current liabilities
Derivatives, Fair Value [Line Items]
Derivatives Liability	(37)	(25)
Derivatives designated as hedging instruments \| Interest rate contracts \| Other long-term liabilities and deferred credits
Derivatives, Fair Value [Line Items]
Derivatives Liability	(112)	(111)
Derivatives designated as hedging instruments \| Foreign currency contracts
Derivatives, Fair Value [Line Items]
Derivatives Asset	29	41
Derivatives Liability	0	(2)
Derivatives designated as hedging instruments \| Foreign currency contracts \| Other current assets
Derivatives, Fair Value [Line Items]
Derivatives Asset	29	0
Derivatives designated as hedging instruments \| Foreign currency contracts \| Deferred charges and other assets
Derivatives, Fair Value [Line Items]
Derivatives Asset	0	41
Derivatives designated as hedging instruments \| Foreign currency contracts \| Other current liabilities
Derivatives, Fair Value [Line Items]
Derivatives Liability	0	(2)
Derivatives designated as hedging instruments \| Foreign currency contracts \| Other long-term liabilities and deferred credits
Derivatives, Fair Value [Line Items]
Derivatives Liability	0	0
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivatives Asset	49	79
Derivatives Liability	(129)	(75)
Derivatives not designated as hedging instruments \| Energy commodity derivative contracts \| Other current assets
Derivatives, Fair Value [Line Items]
Derivatives Asset	45	75
Derivatives not designated as hedging instruments \| Energy commodity derivative contracts \| Deferred charges and other assets
Derivatives, Fair Value [Line Items]
Derivatives Asset	4	4
Derivatives not designated as hedging instruments \| Energy commodity derivative contracts \| Other current liabilities
Derivatives, Fair Value [Line Items]
Derivatives Liability	(116)	(74)
Derivatives not designated as hedging instruments \| Energy commodity derivative contracts \| Other long-term liabilities and deferred credits
Derivatives, Fair Value [Line Items]
Derivatives Liability	$ (13)	$ (1)