v3.26.1
Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Dec. 31, 2024
Accumulated Other Comprehensive Income (Loss) [Roll Forward]                
Stockholders' Equity Attributable to Parent $ 9,053 $ 8,257 $ 9,053 $ 8,257 $ 8,728 $ 8,621 $ 7,989 $ 7,933
Total other comprehensive income (loss) 27 (10) 4 (13)        
Net Unrealized Gains (Losses) on Available-for-sale Securities                
Accumulated Other Comprehensive Income (Loss) [Roll Forward]                
Stockholders' Equity Attributable to Parent 28 (14) 28 (14) 2 25 (4) (1)
Net unrealized losses on available-for-sale securities 26 (10) 3 (13)        
Pension and postretirment 0   0          
Total other comprehensive income (loss) 26   3          
Pension and Postretirement Benefits [Member]                
Accumulated Other Comprehensive Income (Loss) [Roll Forward]                
Stockholders' Equity Attributable to Parent (4) 1 (4) 1 (5) (5) 1 1
Net unrealized losses on available-for-sale securities 0 0 0          
Pension and postretirment 1   1          
Total other comprehensive income (loss) 1   1          
Total Accumulated Other Comprehensive Income (Loss) [Member]                
Accumulated Other Comprehensive Income (Loss) [Roll Forward]                
Stockholders' Equity Attributable to Parent 24 (13) 24 (13) $ (3) $ 20 $ (3) $ 0
Net unrealized losses on available-for-sale securities 26 $ (10) 3 $ (13)        
Pension and postretirment 1   1          
Total other comprehensive income (loss) $ 27   $ 4