v3.25.3
Business Combinations - Narrative (Details)
 3 Months Ended 9 Months Ended
Aug. 01, 2025
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tower_site
Jul. 22, 2025
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agreement
Jun. 30, 2025
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Mar. 03, 2025
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Feb. 18, 2025
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Feb. 03, 2025
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May 24, 2024
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May 01, 2024
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Mar. 09, 2023
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Sep. 30, 2025
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Sep. 30, 2024
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Sep. 30, 2025
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Sep. 30, 2024
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Aug. 05, 2025
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Dec. 31, 2024
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Dec. 20, 2024
Business Combination [Line Items]                                
Goodwill                   $ 13,690,000,000   $ 13,690,000,000     $ 13,005,000,000  
Principal outstanding                   10,027,000,000   10,027,000,000        
Short-term debt assumed for financing of property and equipment                   1,653,000,000 $ 0 1,653,000,000 $ 0      
Equipment installment plan receivables, net                   4,599,000,000   4,599,000,000     4,379,000,000  
Senior Notes                                
Business Combination [Line Items]                                
Principal outstanding                   8,027,000,000   8,027,000,000        
6.700% Senior Notes due 2033 | Senior Notes                                
Business Combination [Line Items]                                
Principal outstanding                           $ 489,000,000    
Interest rate, stated percentage                           6.70%    
6.250% Senior Notes due 2069 | Senior Notes                                
Business Combination [Line Items]                                
Principal outstanding                           $ 393,000,000    
Interest rate, stated percentage                           6.25%    
5.500% Senior Notes due March 2070 | Senior Notes                                
Business Combination [Line Items]                                
Principal outstanding                           $ 401,000,000    
Interest rate, stated percentage                           5.50%    
5.500% Senior Notes due June 2070 | Senior Notes                                
Business Combination [Line Items]                                
Principal outstanding                           $ 395,000,000    
Interest rate, stated percentage                           5.50%    
Ka Ena Corporation | Merger And Unit Purchase Agreement                                
Business Combination [Line Items]                                
Business acquisition, outstanding (percent)                 100.00%              
Total consideration transferred     $ 1,350,000,000           $ 1,350,000,000              
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]                                
Total consideration transferred               $ 1,141,000,000                
Liabilities for deferred consideration                   239,000,000   239,000,000     202,000,000  
Liabilities for post-acquisition                   149,000,000   149,000,000     $ 80,000,000  
Goodwill               777,000,000                
Goodwill expected to be tax deductible               121,000,000                
Increase in deferred tax liabilities               83,000,000                
Accounts receivable               34,000,000                
Total liabilities assumed               $ 506,000,000                
UScellular Wireless Assets Operations                                
Business Combination [Line Items]                                
Total consideration transferred $ 2,855,000,000                              
Goodwill 231,000,000                              
Goodwill expected to be tax deductible 15,000,000                              
Business acquisition, cash transferred 2,811,000,000                              
Short-term debt assumed for financing of property and equipment                       1,700,000,000        
Short-term debt assumed for financing of property and equipment at fair value                   $ 1,700,000,000   $ 1,700,000,000        
Long-term debt $ 1,653,000,000                              
Lessee leasing arrangements, operating leases, term of contract (years) 30 months                              
Customary adjustments period 120 days                              
Spectrum licenses $ 1,730,000,000                              
Accounts receivable 317,000,000                              
Equipment installment plan receivables, net 891,000,000                              
Accounts receivable unpaid principal balances 328,000,000                              
EIP receivable unpaid principal balance 1,100,000,000                              
Total liabilities assumed 3,759,000,000                              
UScellular Wireless Assets Operations | Customer Relationships                                
Business Combination [Line Items]                                
Finite-lived, fair value $ 379,000,000                              
Lease space agreement term (years) 10 years                              
UScellular Wireless Assets Operations | Tradenames                                
Business Combination [Line Items]                                
Finite-lived, fair value $ 18,000,000                              
Lease space agreement term (years) 1 year                              
UScellular Wireless Assets Operations | Purchase Agreement                                
Business Combination [Line Items]                                
Payments for asset acquisition             $ 4,400,000,000                  
Asset acquisition, maximum transferred liabilities incurred             $ 2,000,000,000                  
Business acquisition, cash transferred $ 2,800,000,000                              
Number of towers to be extended tenancy term | tower_site 600                              
Lessee leasing arrangements, operating leases, term of contract (years) 15 years                              
UScellular Wireless Assets Operations | Master License Agreement                                
Business Combination [Line Items]                                
Principal outstanding $ 1,700,000,000                         $ 1,700,000,000    
Number of towers retained | tower_site 2,100                              
Number of towers leased on interim basis | tower_site 1,800                              
Operating lease right-of-use assets $ 1,000,000,000.0                              
Operating lease liabilities 1,000,000,000.0                              
Increase in deferred tax liabilities 261,000,000                              
Deferred tax assets $ 261,000,000                              
Farmers Cellular Telephone Company Acquisition | Purchase Agreement                                
Business Combination [Line Items]                                
Number of separate asset purchase agreements | agreement   3                            
Business acquisition, cash transferred   $ 175,000,000                            
Vistar Media Inc.                                
Business Combination [Line Items]                                
Business acquisition, outstanding (percent)                               100.00%
Total consideration transferred           $ 617,000,000                    
Goodwill           343,000,000                    
Increase in deferred tax liabilities           61,000,000                    
Accounts receivable           157,000,000                    
Total consideration transferred, including settlements of preexisting relationships           621,000,000                    
Total liabilities assumed           193,000,000                    
Vistar Media Inc. | Customer Relationships                                
Business Combination [Line Items]                                
Finite-lived, fair value           201,000,000                    
Vistar Media Inc. | Tradenames                                
Business Combination [Line Items]                                
Finite-lived, fair value           8,000,000                    
Vistar Media Inc. | Other Intangible Assets                                
Business Combination [Line Items]                                
Finite-lived, fair value           $ 55,000,000                    
Vistar Media Inc. | Merger and Unit Purchase Agreement, Amendment No. 1 | Customer Relationships                                
Business Combination [Line Items]                                
Lease space agreement term (years)           10 years                    
Vistar Media Inc. | Merger and Unit Purchase Agreement, Amendment No. 1 | Tradenames                                
Business Combination [Line Items]                                
Lease space agreement term (years)           4 years                    
Vistar Media Inc. | Merger and Unit Purchase Agreement, Amendment No. 1 | Other Intangible Assets                                
Business Combination [Line Items]                                
Lease space agreement term (years)           4 years                    
Blis Holdco Limited                                
Business Combination [Line Items]                                
Business acquisition, outstanding (percent)         100.00%                      
Total consideration transferred         $ 174,000,000                      
Business acquisition, cash transferred       $ 180,000,000                        
Total assets acquired, including goodwill         264,000,000                      
Total liabilities assumed         90,000,000                      
Preliminary goodwill from the Ka’ena Acquisition in 2024         $ 105,000,000