Employee Benefit Plans (Components of Provision for Net Periodic Benefit Cost (Credit)) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 19	$ 22
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Interest cost	$ 108	$ 109
Expected return on plan assets	(169)	(204)
Amortization of prior service cost (credit)	0	0
Amortization of net actuarial (gain) loss	0	(170)
Curtailments	0	(31)
Plan amendment	0	22
Net periodic benefit (credit) cost	(42)	(252)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Interest cost	$ 14	$ 14
Expected return on plan assets	(40)	(42)
Amortization of prior service cost (credit)	(6)	(9)
Amortization of net actuarial (gain) loss	0	(32)
Curtailments	0	(4)
Plan amendment	0	0
Net periodic benefit (credit) cost	$ (29)	$ (70)