Adoption of New Standard Impact on Previously Reported Quarterly Results (Detail) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
 3 Months Ended 9 Months Ended
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Mar. 31, 2015
Mar. 31, 2016
Mar. 31, 2015
Jun. 30, 2015
Income statements:              
Provision for income taxes $ 1,280 $ 837 $ 611 $ 1,532 $ 2,728 $ 4,875  
Net income $ 3,756 $ 5,018 $ 4,902 $ 4,985 $ 13,676 $ 15,388  
Basic earnings per share $ 0.48 $ 0.63 $ 0.61 $ 0.61 $ 1.72 $ 1.87  
Diluted earnings per share $ 0.47 $ 0.62 $ 0.61 $ 0.61 $ 1.70 $ 1.86  
Diluted weighted average shares outstanding 7,985 8,051 8,084 8,237 8,041 8,293  
Cash flows statements:              
Net cash from operations $ 10,367 $ 5,618 $ 8,876 $ 9,601 $ 24,861 $ 22,819  
Net cash used in financing (4,916) (518) (3,930) $ (3,096) (9,364) $ (6,064)  
Balance sheets:              
Common stock and paid-in capital 68,012 67,977 67,811   68,012   $ 68,465
Retained earnings $ 4,954 7,030 7,896   $ 4,954   $ 9,096
As reported              
Income statements:              
Provision for income taxes   857 893        
Net income   $ 4,998 $ 4,620        
Basic earnings per share   $ 0.63 $ 0.58        
Diluted earnings per share   $ 0.62 $ 0.57        
Diluted weighted average shares outstanding   8,028 8,066        
Cash flows statements:              
Net cash from operations   $ 5,598 $ 8,594        
Net cash used in financing   (498) (3,648)        
Balance sheets:              
Common stock and paid-in capital   68,279 68,093        
Retained earnings   $ 6,728 $ 7,614