v3.25.3
Revenue Recognition - Revenue from contracts with customers (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2025
Sep. 30, 2024
Dec. 31, 2024
Dec. 31, 2023
Revenue Recognition            
Revenue $ 257 $ 262 $ 784 $ 753 $ 1,016 $ 981
Lease, grant, and revenue from subsidies            
Revenue Recognition            
Revenue 24 18 71 57    
Data | Consumer Revenue            
Revenue Recognition            
Revenue 59 62 180 186    
Data | Business Revenue            
Revenue Recognition            
Revenue 124 122 375 333    
Wireless | Consumer Revenue            
Revenue Recognition            
Revenue 35 35 104 105    
Wireless | Business Revenue            
Revenue Recognition            
Revenue 8 10 24 31    
Other | Consumer Revenue            
Revenue Recognition            
Revenue 4 12 22 32    
Other | Business Revenue            
Revenue Recognition            
Revenue $ 3 $ 3 $ 8 $ 9