(Summary Of Long-Term Debt) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023	Mar. 31, 2023	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 5,524	$ 5,505
Capitalized leases		55	59
Premiums, discounts, and debt issuance costs		(41)	(42)
Terminated interest rate swaps		54	55
Other		1	2
Total (c)	[1]	5,593	5,579
Long-term Debt, Current Maturities		138	763
Long-term debt		5,455	$ 4,816
Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			3.00%			3.00%
Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			8.70%			8.70%
6.875% notes – due 2023
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 0	$ 87
Debt instrument, interest rate, stated percentage		6.875%	6.875%
Maturity date		2023
7.350% notes – due 2025
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 39	$ 39
Debt instrument, interest rate, stated percentage		7.35%	7.35%
Maturity date		2025
7.750% notes – due 2025
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 22	$ 22
Debt instrument, interest rate, stated percentage		7.75%	7.75%
Maturity date		2025
7.200% notes – due 2026
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 58	$ 58
Debt instrument, interest rate, stated percentage		7.20%	7.20%
Maturity date		2026
6.400% notes – due 2026
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 5	$ 5
Debt instrument, interest rate, stated percentage		6.40%	6.40%
Maturity date		2026
7.150% notes – due 2027
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 7	$ 7
Debt instrument, interest rate, stated percentage		7.15%	7.15%
Maturity date		2027
6.875% notes – due 2029
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 10	$ 10
Debt instrument, interest rate, stated percentage		6.875%	6.875%
Maturity date		2029
5.000% notes – due 2035
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 407	$ 407
Debt instrument, interest rate, stated percentage		5.00%	5.00%
Maturity date		2035
6.650% notes – due 2037
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 3	$ 3
Debt instrument, interest rate, stated percentage		6.65%	6.65%
Maturity date		2037
8.700% notes – due 2038
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 86	$ 86
Debt instrument, interest rate, stated percentage		8.70%	8.70%
Maturity date		2038
7.300% notes – due 2039
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 453	$ 453
Debt instrument, interest rate, stated percentage		7.30%	7.30%
Maturity date		2039
6.000% notes – due 2041
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 585	$ 585
Debt instrument, interest rate, stated percentage		6.00%	6.00%
Maturity date		2041
4.800% notes – due 2044
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 686	$ 686
Debt instrument, interest rate, stated percentage		4.80%	4.80%
Maturity date		2044
5.150% notes – due 2046
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 449	$ 449
Debt instrument, interest rate, stated percentage		5.15%	5.15%
Maturity date		2046
4.400% notes – due 2047
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 647	$ 647
Debt instrument, interest rate, stated percentage		4.40%	4.40%
Maturity date		2047
4.350% notes – due 2048
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 740	$ 740
Debt instrument, interest rate, stated percentage		4.35%	4.35%
Maturity date		2048
Floating rate notes – due 2023 – 2027 (a)
Debt Instrument [Line Items]
Long-term Debt, Gross	[2]	$ 308	$ 732
Environmental and industrial development bonds – due 2023 – 2028 (b)
Debt Instrument [Line Items]
Long-term Debt, Gross	[3]	$ 419	489
Variable Rate [Domain] | Minimum [Member]
Debt Instrument [Line Items]
Maturity date		2023
Variable Rate [Domain] | Maximum [Member]
Debt Instrument [Line Items]
Maturity date		2027
Variable Rate Demand Obligation
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 600	$ 0
Environmental Debt Bond
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage				2.90%	4.00%
Environmental Debt Bond | Minimum [Member]
Debt Instrument [Line Items]
Maturity date		2023
Environmental Debt Bond | Maximum [Member]
Debt Instrument [Line Items]
Maturity date		2028

[1] The fair market value was approximately $5.5 billion at December 31, 2023 and $5.2 billion at December 31, 2022. Debt fair value measurements use Level 2 inputs.

[2] The weighted average interest rate on these notes was 5.4% in 2023 and 4.6% in 2022.

[3] The weighted average interest rate on these bonds was 2.4% in 2023 and 2.4% in 2022.