v3.26.1
Employee Benefits - Costs by Plans (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Defined Benefit Plan Disclosure [Line Items]    
Remeasurement gain, net $ (237)  
Pension    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 48 $ 39
Amortization of prior service cost (credit) 33 28
Expected return on plan assets (177) (134)
Interest cost 119 103
Remeasurement gain, net (18) 0
Other components (43) (3)
Total 5 36
Pension | Cost of services    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 48 34
Pension | Selling, general and administrative expense    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 0 5
Health Care and Life    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 6 9
Amortization of prior service cost (credit) (31) (32)
Expected return on plan assets (7) (7)
Interest cost 129 136
Remeasurement gain, net (219) 0
Other components (128) 97
Total (122) 106
Health Care and Life | Cost of services    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 6 7
Health Care and Life | Selling, general and administrative expense    
Defined Benefit Plan Disclosure [Line Items]    
Service cost $ 0 $ 2