v3.7.0.1
Acquisitions and Divestitures - Additional Information (Detail)
$ in Millions
1 Months Ended 3 Months Ended 12 Months Ended 14 Months Ended
Feb. 20, 2017
USD ($)
Feb. 01, 2017
USD ($)
Dec. 06, 2016
USD ($)
Site
Jul. 23, 2016
USD ($)
Apr. 30, 2017
USD ($)
Mar. 31, 2017
USD ($)
Mar. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Feb. 28, 2017
USD ($)
Dec. 31, 2016
USD ($)
Business Acquisition [Line Items]                    
Pre-tax gain on sale of wireless licenses           $ 126 $ 142      
Goodwill           420        
Real estate assets held and used           85,213       $ 84,751
Non-current assets held for sale           762       $ 613
Advanced Wireless Services Spectrum Licenses                    
Business Acquisition [Line Items]                    
Pre-tax gain on sale of wireless licenses           126        
Acquisitions           1,000        
Data Center Sale with Equinix                    
Business Acquisition [Line Items]                    
Proceeds from dispositions of businesses     $ 3,600              
Real estate assets held and used           600        
Non-current assets held for sale           $ 800        
XO Holdings                    
Business Acquisition [Line Items]                    
Business acquisition, purchase price in cash               $ 100 $ 1,800  
Goodwill   $ 400                
Intangible assets subject to amortization   $ 300                
XO Holdings | Subsequent Event                    
Business Acquisition [Line Items]                    
Business acquisition, cost of subsidiary acquired         $ 200          
Yahoo! Inc.                    
Business Acquisition [Line Items]                    
Business acquisition, purchase price in cash $ 4,480     $ 4,830            
Purchase price reduction due to Purchase Agreement Amendment $ (350)                  
Post-closing liabilities arising from data breach percent retained 50.00%                  
Post-closing liabilities arising from shareholders percent retained 100.00%                  
Yahoo! Inc. | Restricted Stock Units                    
Business Acquisition [Line Items]                    
Outstanding restricted stock units to be awarded to employees who transferred from yahoo       $ 1,000            
United States and Latin America | Data Center Sale with Equinix                    
Business Acquisition [Line Items]                    
Number of data center sites that will be sold | Site     23              
Europe, Asia-Pacific and Canada | Data Center Sale with Equinix                    
Business Acquisition [Line Items]                    
Number of data center sites | Site     27