Postretirement Plans - Schedule of Key Information for All Plans with ABO in Excess of Plan Assets (Details) - Pension - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 49,188	$ 44,470
Fair value of plan assets	45,397	38,866
Projected benefit obligation	$ 49,820	$ 45,002