Financial and Other Derivative Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 1,056	$ 707
Derivative Liabilities	(962)	(597)
Balance Sheet Location [Axis]: us-gaap:DerivativeAssetsCurrent
Derivatives, Fair Value [Line Items]
Derivative Assets	732	482
Balance Sheet Location [Axis]: us-gaap:DerivativeAssetsNoncurrent
Derivatives, Fair Value [Line Items]
Derivative Assets	324	225
Balance Sheet Location [Axis]: us-gaap:DerivativeLiabilitiesCurrent
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(708)	(413)
Balance Sheet Location [Axis]: us-gaap:DerivativeLiabilitiesNoncurrent
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(254)	(184)
Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	43	3
Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	1	0
Derivative Liabilities	(1)	(1)
Natural gas
Derivatives, Fair Value [Line Items]
Derivative Assets	346	372
Derivative Liabilities	(366)	(329)
Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	593	275
Derivative Liabilities	(560)	(235)
Environmental & Other
Derivatives, Fair Value [Line Items]
Derivative Assets	73	57
Derivative Liabilities	(35)	(32)
Derivatives designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	43	3
Derivative Liabilities	0	(1)
Derivatives designated as hedging instruments | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	43	3
Derivative Liabilities	0	0
Derivatives designated as hedging instruments | Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	0	0
Derivative Liabilities	0	(1)
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	1,013	704
Derivative Liabilities	(962)	(596)
Derivatives not designated as hedging instruments | Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	1	0
Derivative Liabilities	(1)	0
Derivatives not designated as hedging instruments | Natural gas
Derivatives, Fair Value [Line Items]
Derivative Assets	346	372
Derivative Liabilities	(366)	(329)
Derivatives not designated as hedging instruments | Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	593	275
Derivative Liabilities	(560)	(235)
Derivatives not designated as hedging instruments | Environmental & Other
Derivatives, Fair Value [Line Items]
Derivative Assets	73	57
Derivative Liabilities	$ (35)	$ (32)