Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Related Party Transaction [Line Items]
Cash distributions	$ 1,600	$ 500	$ 1,100	$ 2,100	$ 1,100
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments Related to TTX	$ 873			$ 873		$ 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	$ 101		$ 96	$ 198	185
Parent Company
Related Party Transaction [Line Items]
Cash distributions				2,100	1,100
Tax payments to Berkshire				581	664
Tax refunds from Berkshire				0	$ 0
Tax Payable, Berkshire	$ 152			$ 152
Payable, Berkshire						$ 170