Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended					9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Related Party Transaction [Line Items]
Cash distributions	$ 700	$ 1,600	$ 500		$ 1,100	$ 2,800	$ 1,100
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments Related to TTX	$ 884					$ 884		$ 848
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	$ 108			$ 92		$ 306	277
Parent Company
Related Party Transaction [Line Items]
Cash distributions						2,800	1,100
Tax payments to Berkshire						904	961
Tax refunds from Berkshire						0	$ 0
Tax Payable, Berkshire	$ 177					$ 177
Payable, Berkshire								$ 170