Segment Information - Reconciliation of Operating Revenues (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating revenues	$ 34,504	$ 32,796	$ 67,989	$ 65,777
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating revenues	33,923	32,227	66,827	64,660
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating revenues	663	633	1,323	1,244
Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating revenues	$ (82)	$ (64)	$ (161)	$ (127)