v3.26.3
Restructuring Costs - Schedule of Activity Related to Reduction Initiative Expenses Incurred (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2026
UScellular Acquisition Restructuring Initiatives    
Restructuring Reserve [Roll Forward]    
Restructuring reserve, beginning balance   $ 91
Expenses Incurred $ 39 214
Cash Payments   (205)
Restructuring reserve, ending balance 100 100
Network Optimization Restructuring Initiatives    
Restructuring Reserve [Roll Forward]    
Restructuring reserve, beginning balance   1
Expenses Incurred 30 131
Cash Payments   (61)
Adjustments for Non-Cash Items   (13)
Restructuring reserve, ending balance 58 58
Contract termination costs | UScellular Acquisition Restructuring Initiatives    
Restructuring Reserve [Roll Forward]    
Restructuring reserve, beginning balance   31
Expenses Incurred 19 111
Cash Payments   (99)
Restructuring reserve, ending balance 43 43
Contract termination costs | Network Optimization Restructuring Initiatives    
Restructuring Reserve [Roll Forward]    
Restructuring reserve, beginning balance   0
Expenses Incurred 9 49
Cash Payments   (36)
Adjustments for Non-Cash Items   0
Restructuring reserve, ending balance 13 13
Severance costs | UScellular Acquisition Restructuring Initiatives    
Restructuring Reserve [Roll Forward]    
Restructuring reserve, beginning balance   59
Expenses Incurred 9 66
Cash Payments   (70)
Restructuring reserve, ending balance 55 55
Network decommissioning | UScellular Acquisition Restructuring Initiatives    
Restructuring Reserve [Roll Forward]    
Restructuring reserve, beginning balance   1
Expenses Incurred 11 37
Cash Payments   (36)
Restructuring reserve, ending balance 2 2
Network decommissioning | Network Optimization Restructuring Initiatives    
Restructuring Reserve [Roll Forward]    
Restructuring reserve, beginning balance   1
Expenses Incurred 21 82
Cash Payments   (25)
Adjustments for Non-Cash Items   (13)
Restructuring reserve, ending balance $ 45 $ 45