Casualty, Environmental and Other Reserves - Schedule of Casualty, Environmental and Other Reserves (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
Current	$ 140	$ 144
Long-term	308	296
Total	448	440
Total Casualty
Loss Contingencies [Line Items]
Current	52	52
Long-term	149	143
Total	201	195
Personal Injury
Loss Contingencies [Line Items]
Current	45	45
Long-term	87	83
Total	132	128
Occupational
Loss Contingencies [Line Items]
Current	7	7
Long-term	62	60
Total	69	67
Environmental
Loss Contingencies [Line Items]
Current	41	41
Long-term	113	113
Total	154	154
Other
Loss Contingencies [Line Items]
Current	47	51
Long-term	46	40
Total	$ 93	$ 91