v3.26.3
Business Combinations - Narrative (Details)
$ in Millions
 3 Months Ended 9 Months Ended
Oct. 09, 2026
USD ($)
shares
Aug. 05, 2025
USD ($)
Aug. 01, 2025
USD ($)
Jul. 22, 2025
USD ($)
agreement
Jun. 30, 2025
USD ($)
Mar. 03, 2025
USD ($)
Feb. 18, 2025
USD ($)
Feb. 03, 2025
USD ($)
May 24, 2024
USD ($)
Mar. 09, 2023
USD ($)
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Dec. 20, 2024
Business Combination [Line Items]                                
Short-term debt assumed for financing of property and equipment                     $ 0 $ 1,653 $ 0 $ 1,653    
Goodwill                     13,665   13,665   $ 13,678  
Ka Ena Corporation | Subsequent Event                                
Business Combination [Line Items]                                
Additional upfront payment to be paid $ 420                              
Business acquisition, cash transferred for earnout obligation $ 164                              
Business acquisition, equity transferred for earnout obligation (in shares) | shares 1,510,371                              
Shares withheld associated with tax obligations (in shares) | shares 102,164                              
Ka Ena Corporation | Merger And Unit Purchase Agreement                                
Business Combination [Line Items]                                
Business acquisition, outstanding (percent)                   100.00%            
Total consideration transferred         $ 1,350         $ 1,350            
Business acquisition, cash acquired (percent)                   39.00%            
Business acquisition, common shares acquired (percent)                   61.00%            
Ka Ena Corporation | Merger and Unit Purchase Agreement, Amendment No. 1                                
Business Combination [Line Items]                                
Additional upfront payment to be paid         420                      
Business combination, potential earnout payment         251                      
Business combination, potential earnout payment for services         $ 169                      
Liabilities for deferred consideration                     251   251   242  
Liabilities for post-acquisition                     $ 169   $ 169   $ 157  
UScellular Wireless Assets Operations                                
Business Combination [Line Items]                                
Total consideration transferred     $ 2,814                          
Business acquisition, cash transferred     2,770                          
Short-term debt assumed for financing of property and equipment   $ 1,700                            
Short-term debt assumed for financing of property and equipment at fair value     1,700                          
Goodwill     206                          
Goodwill expected to be tax deductible     181                          
Total liabilities assumed     3,772                          
UScellular Wireless Assets Operations | Purchase Agreement                                
Business Combination [Line Items]                                
Payments for asset acquisition                 $ 4,400              
Asset acquisition, maximum transferred liabilities incurred                 $ 2,000              
Business acquisition, cash transferred     $ 2,800                          
Farmers Cellular Telephone Company Acquisition | Purchase Agreement                                
Business Combination [Line Items]                                
Number of separate asset purchase agreements | agreement       3                        
Business acquisition, cash transferred       $ 175                        
Vistar Media Inc.                                
Business Combination [Line Items]                                
Business acquisition, outstanding (percent)                               100.00%
Goodwill               $ 341                
Total consideration transferred, including settlements of preexisting relationships               621                
Total liabilities assumed               $ 190                
Blis Holdco Limited                                
Business Combination [Line Items]                                
Business acquisition, outstanding (percent)             100.00%                  
Total consideration transferred             $ 174                  
Business acquisition, cash transferred           $ 180                    
Goodwill             103                  
Total assets acquired, including goodwill             263                  
Total liabilities assumed             $ 89