v3.26.1
Postretirement Benefit Plans (Change in Fair Value of Plan Assets) (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]      
Fair value of plan assets at beginning of period   $ 1,257  
Fair value of plan assets at end of period   1,191 $ 1,257
Pension Benefits [Member]      
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]      
Fair value of plan assets at beginning of period   1,257 1,276
Actual return on plan assets   73 24
Members' contributions   6 6
Benefits paid $ (15) (98) (93)
Company contributions   46 56
Settlements $ (94) (115) (9)
Other   (4) (3)
Currency gains   26 0
Fair value of plan assets at end of period   $ 1,191 $ 1,257