v3.26.1
Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
Movement in Accumulated Other Comprehensive Income [Roll Forward]            
Beginning balance $ 29,315 $ 28,798 $ 27,607 $ 26,921 $ 28,798 $ 26,921
Other comprehensive income, net of income taxes 6 6 0 2 12 2
Ending balance 29,698 29,315 27,620 27,607 29,698 27,620
Pension and Non-Pension Postretirement Benefit Plan Items            
Movement in Accumulated Other Comprehensive Income [Roll Forward]            
Beginning balance (784) (795) (755) (765) (795) (765)
OCI before reclassifications (1)   1   3 5
Amounts reclassified from AOCI 7   5   14 11
Other comprehensive income, net of income taxes 6   6   17 16
Ending balance (778) (784) (749) (755) (778) (749)
Total            
Movement in Accumulated Other Comprehensive Income [Roll Forward]            
Beginning balance (756) (762) (718) (720) (762) (720)
OCI before reclassifications 1   (3)   1 (6)
Amounts reclassified from AOCI 5   3   11 8
Other comprehensive income, net of income taxes 6 6 0 2 12 2
Ending balance (750) (756) (718) (718) (750) (718)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent            
Movement in Accumulated Other Comprehensive Income [Roll Forward]            
Beginning balance 28 33 37 45 33 45
OCI before reclassifications 2   (4)   (2) (11)
Amounts reclassified from AOCI (2)   (2)   (3) (3)
Other comprehensive income, net of income taxes 0   (6)   (5) (14)
Ending balance $ 28 $ 28 $ 31 $ 37 $ 28 $ 31