v3.26.1
Shareholders' Equity - Changes in Accumulated Other Comprehensive Loss by Component (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
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance $ 11,037 $ 10,837 $ 10,534 $ 10,332 $ 10,837 $ 10,332
Amounts reclassified from accumulated other comprehensive income (loss) 0   1   0 (3)
Other comprehensive (loss) income before reclassifications     2   2 (4)
Net other comprehensive income (loss) 0 2 3 (10) 2 (7)
Ending balance 11,665 11,037 10,682 10,534 11,665 10,682
Employee Benefit Plan Funded Status            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance (95) (95) (95) (95) (95) (95)
Amounts reclassified from accumulated other comprehensive income (loss) 0   0   0 0
Other comprehensive (loss) income before reclassifications     0   0 0
Net other comprehensive income (loss) 0   0   0 0
Ending balance (95) (95) (95) (95) (95) (95)
Amortization of Prior Service Cost            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 1 1 1 1 1 1
Amounts reclassified from accumulated other comprehensive income (loss) 0   0   0 0
Other comprehensive (loss) income before reclassifications     0   0 0
Net other comprehensive income (loss) 0   0   0 0
Ending balance 1 1 1 1 1 1
Amortization of Actuarial Loss            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 75 75 74 74 75 74
Amounts reclassified from accumulated other comprehensive income (loss) 0   1   0 1
Other comprehensive (loss) income before reclassifications     0   0 0
Net other comprehensive income (loss) 0   1   0 1
Ending balance 75 75 75 74 75 75
Gain (Loss) on Cash Flow Hedges            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 28 26 22 30 26 30
Amounts reclassified from accumulated other comprehensive income (loss) (1)   0   (1) 0
Other comprehensive (loss) income before reclassifications     3   2 (5)
Net other comprehensive income (loss) (1)   3   1 (5)
Ending balance 27 28 25 22 27 25
Gain (Loss) on Fixed-Income Securities            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance (1) (1) 0 2 (1) 2
Amounts reclassified from accumulated other comprehensive income (loss) 1   0   1 (4)
Other comprehensive (loss) income before reclassifications     (1)   0 1
Net other comprehensive income (loss) 1   (1)   1 (3)
Ending balance 0 (1) (1) 0 0 (1)
Accumulated Other Comprehensive Income (Loss)            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 8 6 2 12 6 12
Net other comprehensive income (loss)   2 3 (10)    
Ending balance $ 8 $ 8 $ 5 $ 2 $ 8 $ 5