Casualty, Environmental and Other Reserves - Schedule of Casualty, Environmental and Other Reserves (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Loss Contingencies [Line Items]
Current	$ 158	$ 149
Long-term	304	313
Total	462	462
Total Casualty
Loss Contingencies [Line Items]
Current	61	58
Long-term	149	150
Total	210	208
Personal Injury
Loss Contingencies [Line Items]
Current	54	51
Long-term	95	91
Total	149	142
Occupational
Loss Contingencies [Line Items]
Current	7	7
Long-term	54	59
Total	61	66
Environmental
Loss Contingencies [Line Items]
Current	39	37
Long-term	110	114
Total	149	151
Other
Loss Contingencies [Line Items]
Current	58	54
Long-term	45	49
Total	$ 103	$ 103