Financial and Other Derivative Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 609	$ 694
Derivative Liabilities	(505)	(605)
Current derivative assets
Derivatives, Fair Value [Line Items]
Derivative Assets	420	488
Current derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(348)	(441)
Noncurrent derivative assets
Derivatives, Fair Value [Line Items]
Derivative Assets	189	206
Noncurrent derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(157)	(164)
Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	0	20
Derivative Liabilities	0	0
Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	0	1
Derivative Liabilities	(1)	(1)
Natural gas
Derivatives, Fair Value [Line Items]
Derivative Assets	344	428
Derivative Liabilities	(300)	(410)
Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	191	187
Derivative Liabilities	(163)	(150)
Environmental & Other
Derivatives, Fair Value [Line Items]
Derivative Assets	74	58
Derivative Liabilities	(41)	(44)
Derivatives designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	0	20
Derivative Liabilities	(1)	(1)
Derivatives designated as hedging instruments | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	0	20
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	609	674
Derivative Liabilities	(504)	(604)
Derivatives not designated as hedging instruments | Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	0	1
Derivative Liabilities	0	0
Derivatives not designated as hedging instruments | Natural gas
Derivatives, Fair Value [Line Items]
Derivative Assets	344	428
Derivative Liabilities	(300)	(410)
Derivatives not designated as hedging instruments | Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	191	187
Derivative Liabilities	(163)	(150)
Derivatives not designated as hedging instruments | Environmental & Other
Derivatives, Fair Value [Line Items]
Derivative Assets	74	58
Derivative Liabilities	$ (41)	$ (44)