Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property leases
Operating Leases
Within 1 year	$ 688
Between 1 and 2 years	478
Between 2 and 3 years	414
Between 3 and 4 years	357
Between 4 and 5 years	263
Thereafter	1,051
Total lease payments	3,251
Less: Imputed interest	(558)
Total	2,693	$ 2,439
Buses and support vehicles
Operating Leases
Within 1 year	83
Between 1 and 2 years	30
Between 2 and 3 years	8
Between 3 and 4 years	2
Between 4 and 5 years	0
Thereafter	0
Total lease payments	123
Less: Imputed interest	(4)
Total	119	86
Finance Leases
Within 1 year	59
Between 1 and 2 years	0
Between 2 and 3 years	0
Between 3 and 4 years	108
Between 4 and 5 years	5
Thereafter	0
Total lease payments	172
Less: Imputed interest	0
Total	$ 172	$ 176