v3.24.0.1
Restructuring Costs - Schedule of Activity Related to Expenses Incurred and Cash Payments Made (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Restructuring Reserve [Roll Forward]      
Expenses Incurred $ 337 $ 1,196 $ 215
Contract termination costs      
Restructuring Reserve [Roll Forward]      
Expenses Incurred 45 231 14
Severance costs      
Restructuring Reserve [Roll Forward]      
Expenses Incurred 3 169 17
Network decommissioning      
Restructuring Reserve [Roll Forward]      
Expenses Incurred 289 796 $ 184
Merger Restructuring Initiatives      
Restructuring Reserve [Roll Forward]      
Restructuring Reserve, Beginning Balance 470    
Expenses Incurred 337    
Cash Payments (672)    
Adjustments for Non-Cash Items (23)    
Restructuring Reserve, Ending Balance 112 470  
Merger Restructuring Initiatives | Contract termination costs      
Restructuring Reserve [Roll Forward]      
Restructuring Reserve, Beginning Balance 190    
Expenses Incurred 45    
Cash Payments (217)    
Adjustments for Non-Cash Items 0    
Restructuring Reserve, Ending Balance 18 190  
Merger Restructuring Initiatives | Severance costs      
Restructuring Reserve [Roll Forward]      
Restructuring Reserve, Beginning Balance 0    
Expenses Incurred 3    
Cash Payments (6)    
Adjustments for Non-Cash Items 3    
Restructuring Reserve, Ending Balance 0 0  
Merger Restructuring Initiatives | Network decommissioning      
Restructuring Reserve [Roll Forward]      
Restructuring Reserve, Beginning Balance 280    
Expenses Incurred 289    
Cash Payments (449)    
Adjustments for Non-Cash Items (26)    
Restructuring Reserve, Ending Balance $ 94 $ 280