Debt (Schedule of Debt - 1) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Finance leases	$ 1,261	$ 891
Net unamortized premiums, discounts and debt issuance costs	907	186
Total debt	19,934	15,369
9.125% Debentures due 2021 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt at face value	$ 0	123
Stated interest rate	9.125%
2.4% Notes due 2022 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 329	329
Stated interest rate	2.40%
7.65% Debentures due 2023 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt at face value	$ 78	78
Stated interest rate	7.65%
3.35% Notes due 2024 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 426	426
Stated interest rate	3.35%
8.2% Debentures due 2025 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt at face value	$ 134	134
Stated interest rate	8.20%
3.35% Notes due 2025 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 199	199
Stated interest rate	3.35%
6.875% Debentures due 2026 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt at face value	$ 67	67
Stated interest rate	6.875%
4.95% Notes due 2026 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 1,250	1,250
Stated interest rate	4.95%
7.8% Debentures due 2027 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt at face value	$ 203	203
Stated interest rate	7.80%
3.75% Notes due 2027 - 1 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 981	0
Stated interest rate	3.75%
3.75% Notes due 2027 - 2 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 19	0
Stated interest rate	3.75%
4.3% Notes due 2028 - 1 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 973	0
Stated interest rate	4.30%
4.3% Notes due 2028 - 2 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 27	0
Stated interest rate	4.30%
7.375% Debentures due 2029 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt at face value	$ 92	92
Stated interest rate	7.375%
7% Debentures due 2029 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt at face value	$ 200	200
Stated interest rate	7.00%
6.95% Notes due 2029 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 1,549	1,549
Stated interest rate	6.95%
8.125% Notes due 2030 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 390	390
Stated interest rate	8.125%
2.4% Notes due 2031 - 1 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 489	0
Stated interest rate	2.40%
2.4% Notes due 2031 - 2 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 11	0
Stated interest rate	2.40%
7.2% Notes due 2031 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 575	575
Stated interest rate	7.20%
7.25% Notes due 2031 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 500	500
Stated interest rate	7.25%
7.4% Notes due 2031 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 500	500
Stated interest rate	7.40%
5.9% Notes due 2032 [Member[ | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 505	505
Stated interest rate	5.90%
4.15% Notes due 2034 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 246	246
Stated interest rate	4.15%
5.95% Notes due 2036 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 500	500
Stated interest rate	5.95%
5.951% Notes due 2037 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 645	645
Stated interest rate	5.951%
5.9% Notes due 2038 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 600	600
Stated interest rate	5.90%
6.5% Notes due 2039 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 2,750	2,750
Stated interest rate	6.50%
4.3% Notes due 2044 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 750	750
Stated interest rate	4.30%
5.95% Notes due 2046 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 500	500
Stated interest rate	5.95%
7.9% Debentures due 2047 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt at face value	$ 60	60
Stated interest rate	7.90%
4.875% Notes due 2047 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 800	0
Stated interest rate	4.875%
4.85% Notes due 2048 - 1 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 590	0
Stated interest rate	4.85%
4.85% Notes due 2048 - 2 [Member] | Notes Payable To Banks [Member]
Debt Instrument [Line Items]
Debt at face value	$ 10	0
Stated interest rate	4.85%
Floating Rate Notes due 2022 [Member] | Floating Rate Notes [Member]
Debt Instrument [Line Items]
Debt at face value	$ 500	$ 500
Floating Rate Notes due 2022 [Member] | Floating Rate Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Stated interest rate	1.02%	1.12%
Floating Rate Notes due 2022 [Member] | Floating Rate Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Stated interest rate	1.12%	2.81%
Marine Terminal Revenue Refunding Bonds due 2031 [Member] | Variable Rate Debt Bonds [Member]
Debt Instrument [Line Items]
Debt at face value	$ 265	$ 265
Marine Terminal Revenue Refunding Bonds due 2031 [Member] | Variable Rate Debt Bonds [Member] | Minimum [Member]
Debt Instrument [Line Items]
Stated interest rate	0.04%	0.10%
Marine Terminal Revenue Refunding Bonds due 2031 [Member] | Variable Rate Debt Bonds [Member] | Maximum [Member]
Debt Instrument [Line Items]
Stated interest rate	0.15%	7.50%
Industrial Development Bonds due 2035 [Member] | Variable Rate Debt Bonds [Member]
Debt Instrument [Line Items]
Debt at face value	$ 18	$ 18
Industrial Development Bonds due 2035 [Member] | Variable Rate Debt Bonds [Member] | Minimum [Member]
Debt Instrument [Line Items]
Stated interest rate	0.04%	0.11%
Industrial Development Bonds due 2035 [Member] | Variable Rate Debt Bonds [Member] | Maximum [Member]
Debt Instrument [Line Items]
Stated interest rate	0.12%	7.50%
Other Debt [Member]
Debt Instrument [Line Items]
Debt at face value	$ 35	$ 38
Commercial Paper [Member] | Commercial Paper Variable Rate [Member]
Debt Instrument [Line Items]
Debt at face value	$ 0	$ 300
Commercial Paper [Member] | Commercial Paper Variable Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Stated interest rate	0.05%
Commercial Paper [Member] | Commercial Paper Variable Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Stated interest rate	0.22%