Postretirement Benefit Plans - Components of Net Periodic Pension Costs (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Service cost	$ 12	$ 15	$ 18
Interest cost on the projected benefit obligation	18	8	6
Expected return on plan assets	(6)	(5)	(6)
Amortization of net (gain) loss	0	9	10
Curtailments & settlements	0	0	0
Net periodic cost	$ 24	$ 27	$ 28