Retirement Plans - Components of Net Periodic Benefit Cost for Pension Plans & Postretirement Medical Plan (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Pension prior service cost	$ 35	$ 35	$ 0	$ 0
Settlement loss		0	(17)	(2)
Net periodic benefic cost excluding service cost		(22)	(39)	(114)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service costs		40	35	44
Interest costs		91	97	69
Expected return on plan assets		(155)	(156)	(196)
Defined Benefit Plan, Amortization of Gain (Loss)		(5)	(3)	(11)
Pension prior service cost		35	0	0
Settlement loss		0	(17)	(2)
Net Periodic Benefit Cost		16	(4)	(70)
Postretirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Service costs		3	3	3
Interest costs		3	2	1
Expected return on plan assets		0	0	0
Defined Benefit Plan, Amortization of Gain (Loss)		1	2	1
Pension prior service cost		0	0	0
Settlement loss		0	0	0
Net Periodic Benefit Cost		$ 5	$ 3	$ 3