v3.20.2
Preferred Shares (Narrative) (Details)
$ / shares in Units, $ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
$ / shares
shares
Jun. 30, 2020
€ / shares
Class of Stock [Line Items]      
Preferred stock, authorized (in shares) 10,000,000 10,000,000  
Preferred stock, par value | $ / shares $ 1.00 $ 1  
Preferred stock, dividend payment terms So long as the preferred dividends are declared and paid on a timely basis on each series of preferred shares, there are no limitations on our ability to declare a dividend on or repurchase AT&T common shares.    
Preferred Stock, Redemption Terms The preferred shares are optionally redeemable by AT&T at the liquidation price generally on or after five years from the issuance date, or upon certain other contingent events.    
Series A Preferred Stock [Member]      
Class of Stock [Line Items]      
Preferred stock, par value | $ / shares $ 1 $ 1  
Preferred stock, outstanding (in shares) 48,000 48,000  
Preferred stock, issued (in shares) 48,000 48,000  
Preferred stock, value, issued | $ $ 0 $ 0  
Preferred stock, liquidation preference per share | $ / shares $ 25,000 $ 25,000  
Preferred stock, dividend rate 5.00% 5.00%  
Series B Preferred Stock [Member]      
Class of Stock [Line Items]      
Preferred stock, par value | $ / shares $ 1    
Preferred stock, outstanding (in shares) 20,000 0  
Preferred stock, issued (in shares) 20,000 0  
Preferred stock, value, issued | $ $ 0 $ 0  
Preferred stock, liquidation preference per share | € / shares     € 100,000
Preferred stock, dividend rate 2.875%    
Series C Preferred Stock [Member]      
Class of Stock [Line Items]      
Preferred stock, par value | $ / shares $ 1    
Preferred stock, outstanding (in shares) 70,000 0  
Preferred stock, issued (in shares) 70,000 0  
Preferred stock, value, issued | $ $ 0 $ 0  
Preferred stock, liquidation preference per share | $ / shares $ 25,000    
Preferred stock, dividend rate 4.75%