v3.26.1
Accumulated Other Comprehensive Income AOCI by Component (Details) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]    
Beginning Balance $ 498 $ 581
Other comprehensive income (loss), net before reclassifications 0 1
Reclassification from AOCI, Current Period, Tax 2 3
Ending Balance 489 570
Equity Method Investments    
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]    
Beginning Balance 9 9
Other comprehensive income (loss), net before reclassifications 0 1
Reclassification from AOCI, Current Period, Tax 0 0
Ending Balance 9 10
Pension and Retiree Health and Welfare Benefit Items    
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]    
Beginning Balance 489 572
Other comprehensive income (loss), net before reclassifications 0 0
Reclassification from AOCI, Current Period, Tax 2 3
Ending Balance 480 560
Amortization of actuarial (gains) losses    
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]    
Amortization of actuarial (gains) losses (11) (15)
Amortization of actuarial (gains) losses | Equity Method Investments    
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]    
Amortization of actuarial (gains) losses 0 0
Amortization of actuarial (gains) losses | Pension and Retiree Health and Welfare Benefit Items    
Other Comprehensive Income (Loss) Net of Tax, Period Change [Abstract]    
Amortization of actuarial (gains) losses $ (11) $ (15)