Quarterly report pursuant to Section 13 or 15(d)

Roll-forward of Common Stock, Additional Paid-in Capital, and Retained Earnings Accounts (Detail)

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Roll-forward of Common Stock, Additional Paid-in Capital, and Retained Earnings Accounts (Detail) (USD $)
In Millions, except Per Share data, unless otherwise specified
 3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Stockholders Equity Note [Roll Forward]        
Common stock purchases     (18.5) (31.7)
Balance at beginning of period     $ 7,035  
Net income 469 1,072 2,555 3,079
Common stock purchases     (1,392) (2,190)
Balance at end of period 7,529   7,529  
Class A common stock
        
Stockholders Equity Note [Roll Forward]        
Balance at beginning of period       258
Common stock purchases     (6.0) (6.0)
Stock award plans     5 4
Common stock issuances     3 3
Conversions of Class A to Class B common stock     (11) (15)
Balance at end of period 231 244 231 244
Balance at beginning of period     3 3
Balance at end of period 3 3 3 3
Class B common stock
        
Stockholders Equity Note [Roll Forward]        
Balance at beginning of period       735
Common stock purchases     (13.0) (26.0)
Conversions of Class A to Class B common stock     11 15
Balance at end of period 723 724 723 724
Balance at beginning of period     7 7
Balance at end of period 7 7 7 7
Additional Paid-in Capital
        
Stockholders Equity Note [Roll Forward]        
Balance at beginning of period     0 0
Stock award plans     414 375
Common stock issuances     207 192
Option premiums received (paid)     206 (150)
Common stock purchases     (827) (417)
Balance at end of period 0 0 0 0
StockRepurchaseProgramRepurchaseAmountUnsettled 0 0 0 0
Retained Earnings
        
Stockholders Equity Note [Roll Forward]        
Balance at beginning of period     10,128 10,604
Net income     2,555 3,079
Dividends ($0.57 and $0.52 per share)     (1,670) (1,553)
Common stock purchases     (565) (1,773)
Balance at end of period $ 10,448 $ 10,357 $ 10,448 $ 10,357
Common stock, cash paid for dividends, per share $ 1.71 $ 1.56