v3.25.4
Employee Compensation and Benefit Plans - Schedule of Pension Plan (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 20, 2024
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Defined Benefit Plan, Plan Assets, Allocation [Line Items]        
Expected long-term rate of return on plan assets   8.00% 7.00%  
Actual rate of return on plan assets during period   16.00% 6.00%  
Expected long-term rate of return on investments   8.00%    
Interest on projected benefit obligations   $ 50 $ 83 $ 86
Gain on settlement and amortization of actuarial gain   (8) (119) (59)
Expected return on pension plan assets   (52) (99) (97)
Net pension benefit   $ (10) $ (135) (70)
Percent at quoted price   13.00% 26.00%  
Percent at similar assets   76.00% 62.00%  
Percent supported at unobservable inputs   11.00% 12.00%  
Postretirement benefit plan assets   $ 732 $ 626  
Projected benefit obligations   908 895  
Underfunded plan   $ 176 $ 269  
Discount rate   6.00% 6.00%  
Contributions to benefit plan   $ 66 $ 52 $ 32
Expected future contributions   31    
Expected payment, year one   54    
Expected payment, years two and three   114    
Expected payment, years four and five   122    
Expected payment, thereafter   $ 323    
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]   Other (expense) income, net Other (expense) income, net Other (expense) income, net
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]   Other (expense) income, net Other (expense) income, net Other (expense) income, net
Sprint Retirement Pension Plan        
Defined Benefit Plan, Plan Assets, Allocation [Line Items]        
Settlement for a portion of retiree obligations $ 572      
Gain on settlement of pension plan obligation $ 80      
Defined Benefit Plan, Equity Securities, US        
Defined Benefit Plan, Plan Assets, Allocation [Line Items]        
Target allocation, percentage   51.00%    
Fixed Income Securities        
Defined Benefit Plan, Plan Assets, Allocation [Line Items]        
Target allocation, percentage   30.00%    
Defined Benefit Plan, Real Estate        
Defined Benefit Plan, Plan Assets, Allocation [Line Items]        
Target allocation, percentage   19.00%