Segment Information - Summary of Reconciliation of Segment Operating Revenues (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues	$ 134,788	$ 133,974	$ 136,835
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues	132,435	131,748	134,578
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues	2,609	2,479	2,510
Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues	$ (256)	$ (253)	$ (253)