(Summary Of Long-Term Debt) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 5,505	$ 5,497
Capitalized leases		59	66
Premiums, discounts, and debt issuance costs		(42)	(48)
Terminated interest rate swaps		55	58
Other (c)	[1]	2	6
Total (d)	[2]	5,579	5,579
Long-term Debt, Current Maturities		763	196
Long-term debt		4,816	5,383
6.875% notes – due 2023
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 87	$ 94
Debt instrument, interest rate, stated percentage		6.875%	6.875%
7.350% notes – due 2025
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 39	$ 44
Debt instrument, interest rate, stated percentage		7.35%	7.35%
7.750% notes – due 2025
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 22	$ 31
Debt instrument, interest rate, stated percentage		7.75%	7.75%
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%
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%
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%
6.875% notes – due 2029
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 10	$ 37
Debt instrument, interest rate, stated percentage		6.875%	6.875%
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%
6.650% notes – due 2037
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 3	$ 4
Debt instrument, interest rate, stated percentage		6.65%	6.65%
8.700% notes – due 2038
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 86	$ 265
Debt instrument, interest rate, stated percentage		8.70%	8.70%
7.300% notes – due 2039
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 453	$ 722
Debt instrument, interest rate, stated percentage		7.30%	7.30%
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%
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%
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%
4.400% notes – due 2047
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 647	$ 648
Debt instrument, interest rate, stated percentage		4.40%	4.40%
4.350% notes – due 2048
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 740	$ 744
Debt instrument, interest rate, stated percentage		4.35%	4.35%
Floating rate notes – due 2023 – 2027 (a)
Debt Instrument [Line Items]
Long-term Debt, Gross	[3]	$ 732	$ 222
Environmental and industrial development bonds – due 2023 – 2028 (b)
Debt Instrument [Line Items]
Long-term Debt, Gross	[4]	$ 489	$ 489

[1] Includes $0 million and $1 million of fair market value adjustments as of December 31, 2022 and 2021, respectively.

[2] The fair market value was approximately $5.2 billion at December 31, 2022 and $7.1 billion at December 31, 2021. Debt fair value measurements use Level 2 inputs.

[3] The weighted average interest rate on these notes was 4.6% in 2022 and 1.4% in 2021.

[4] The weighted average interest rate on these bonds was 2.4% in 2022 and 3.2% in 2021.