v3.26.3
Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Jun. 30, 2026
Mar. 31, 2026
Sep. 30, 2025
Mar. 31, 2025
Sep. 30, 2026
Sep. 30, 2025
Movement in Accumulated Other Comprehensive Income [Roll Forward]              
Beginning balance $ 29,698 $ 29,315 $ 28,798 $ 27,620 $ 26,921 $ 28,798 $ 26,921
Other comprehensive income, net of income taxes 17 6 6 3 2 29 5
Ending balance 30,132 29,698 29,315 28,113 27,607 30,132 28,113
Pension and Non-Pension Postretirement Benefit Plan Items              
Movement in Accumulated Other Comprehensive Income [Roll Forward]              
Beginning balance (778)   (795) (749) (765) (795) (765)
OCI before reclassifications 0     0   3 5
Amounts reclassified from AOCI 7     5   21 16
Other comprehensive income, net of income taxes 7     5   24 21
Ending balance (771) (778)   (744)   (771) (744)
Total              
Movement in Accumulated Other Comprehensive Income [Roll Forward]              
Beginning balance (750) (756) (762) (718) (720) (762) (720)
OCI before reclassifications 12     (1)   13 (6)
Amounts reclassified from AOCI 5     4   16 11
Other comprehensive income, net of income taxes 17 6 6 3 2 29 5
Ending balance (733) (750) (756) (715) (718) (733) (715)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent              
Movement in Accumulated Other Comprehensive Income [Roll Forward]              
Beginning balance 28   $ 33 31 $ 45 33 45
OCI before reclassifications 12     (1)   10 (11)
Amounts reclassified from AOCI (2)     (1)   (5) (5)
Other comprehensive income, net of income taxes 10     (2)   5 (16)
Ending balance $ 38 $ 28   $ 29   $ 38 $ 29