Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Related Party Transaction [Line Items]
Cash distributions	$ 1,000	$ 1,500	$ 700	$ 700	$ 1,600	$ 500	$ 3,200	$ 2,800
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments Related to TTX	$ 922						$ 922		$ 891
TTX Company
Related Party Transaction [Line Items]
Ownership Percentage in TTX Company	17.40%						17.40%
TTX Company
Related Party Transaction [Line Items]
Car Hire Expenditures with TTX	$ 113			$ 108			$ 326	306
Parent Company
Related Party Transaction [Line Items]
Cash distributions							3,200	2,800
Tax payments to Berkshire							877	904
Tax refunds from Berkshire							0	$ 0
Tax Receivable, Berkshire	$ 41						$ 41
Payable, Berkshire									$ 86