v3.26.1
Restructuring Costs - Schedule of Activity Related to Reduction Initiative Expenses Incurred (Details)
$ in Millions
 3 Months Ended
Mar. 31, 2026
USD ($)
UScellular Acquisition Restructuring Initiatives  
Restructuring Cost and Reserve [Line Items]  
Restructuring reserve, beginning balance $ 91
Expenses Incurred 85
Cash Payments (55)
Restructuring reserve, ending balance 121
Network Optimization Restructuring Initiatives  
Restructuring Cost and Reserve [Line Items]  
Restructuring reserve, beginning balance 1
Expenses Incurred 65
Cash Payments (26)
Restructuring reserve, ending balance 40
Contract termination costs | UScellular Acquisition Restructuring Initiatives  
Restructuring Cost and Reserve [Line Items]  
Restructuring reserve, beginning balance 31
Expenses Incurred 41
Cash Payments (32)
Restructuring reserve, ending balance 40
Contract termination costs | Network Optimization Restructuring Initiatives  
Restructuring Cost and Reserve [Line Items]  
Restructuring reserve, beginning balance 0
Expenses Incurred 27
Cash Payments (14)
Restructuring reserve, ending balance 13
Severance costs | UScellular Acquisition Restructuring Initiatives  
Restructuring Cost and Reserve [Line Items]  
Restructuring reserve, beginning balance 59
Expenses Incurred 26
Cash Payments (8)
Restructuring reserve, ending balance 77
Network decommissioning | UScellular Acquisition Restructuring Initiatives  
Restructuring Cost and Reserve [Line Items]  
Restructuring reserve, beginning balance 1
Expenses Incurred 18
Cash Payments (15)
Restructuring reserve, ending balance 4
Network decommissioning | Network Optimization Restructuring Initiatives  
Restructuring Cost and Reserve [Line Items]  
Restructuring reserve, beginning balance 1
Expenses Incurred 38
Cash Payments (12)
Restructuring reserve, ending balance $ 27