Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Related Party Transaction [Line Items]
Cash distributions	$ 1,000	$ 700
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments Related to TTX	$ 936		$ 930
TTX Company
Related Party Transaction [Line Items]
Ownership Percentage in TTX Company	17.40%
TTX Company
Related Party Transaction [Line Items]
Car Hire Expenditures with TTX	$ 103	106
Parent Company
Related Party Transaction [Line Items]
Cash distributions	1,000	700
Tax payments to Berkshire	0	0
Tax refunds from Berkshire	0	$ 0
Tax Payable, Berkshire	$ 393
Payable, Berkshire			$ 94