Accumulated Other Comprehensive Income (Loss) - Reclassifications of Accumulated Other Comprehensive Income to Consolidated Statement of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Schedule Of Reclassification Of Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	$ 0	$ 1	$ 1	$ 2
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Schedule Of Reclassification Of Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	(3)	(3)	(8)
Reclassification out of Accumulated Other Comprehensive Income | Pension and Postretirement Liability Adjustment
Schedule Of Reclassification Of Accumulated Other Comprehensive Income Loss [Line Items]
Total	$ 0	$ (2)	$ (2)	$ (6)