Casualty, Environmental and Other Reserves - Balance Sheet Presentation (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Contingencies [Line Items]
Current	$ 118	$ 90
Long-term	250	224
Total	368	314	$ 305	$ 324
Casualty
Contingencies [Line Items]
Current	44	49
Long-term	136	147
Total	180	196	187	199
Personal Injury
Contingencies [Line Items]
Current	37	38
Long-term	81	93
Total	118	131
Occupational
Contingencies [Line Items]
Current	7	11
Long-term	55	54
Total	62	65
Environmental
Contingencies [Line Items]
Current	37	23
Long-term	71	53
Total	108	76	74	80
Other
Contingencies [Line Items]
Current	37	18
Long-term	43	24
Total	$ 80	$ 42	$ 44	$ 45