Other Nonoperating Income, Net - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Component of Other Operating Income and Expense [Line Items]
Other nonoperating income, net	$ 58	$ 62	$ 53
Other Nonoperating Income, Net
Component of Other Operating Income and Expense [Line Items]
Gain on repurchase of bond			12
Interest income	40	47	14
Third-party railroad track maintenance expense	$ 10	$ 9	$ 8