Financial and Other Derivative Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 723	$ 707
Derivative Liabilities	(750)	(597)
Current derivative assets
Derivatives, Fair Value [Line Items]
Derivative Assets	536	482
Current derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(556)	(413)
Noncurrent derivative assets
Derivatives, Fair Value [Line Items]
Derivative Assets	187	225
Noncurrent derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(194)	(184)
Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	8	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	289	372
Derivative Liabilities	(333)	(329)
Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	357	275
Derivative Liabilities	(370)	(235)
Environmental & Other
Derivatives, Fair Value [Line Items]
Derivative Assets	68	57
Derivative Liabilities	(46)	(32)
Derivatives designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	8	3
Derivative Liabilities	(1)	(1)
Derivatives designated as hedging instruments | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	8	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	(1)	(1)
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	715	704
Derivative Liabilities	(749)	(596)
Derivatives not designated as hedging instruments | Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	1	0
Derivative Liabilities	0	0
Derivatives not designated as hedging instruments | Natural gas
Derivatives, Fair Value [Line Items]
Derivative Assets	289	372
Derivative Liabilities	(333)	(329)
Derivatives not designated as hedging instruments | Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	357	275
Derivative Liabilities	(370)	(235)
Derivatives not designated as hedging instruments | Environmental & Other
Derivatives, Fair Value [Line Items]
Derivative Assets	68	57
Derivative Liabilities	$ (46)	$ (32)