Common Stock (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2011
Summary of company's activity in stock option plan for 2011
Shares Subject to Option, Outstanding, Beginning Balance	50,711,586
Shares Subject to Option, Granted	7,100,503
Shares Subject to Option, Exercised	(16,800,778)
Shares Subject to Options, Cancelled	(54,489)
Shares Subject to Option, Outstanding, Ending Balance	40,956,822
Shares Subject to Options, Exercisable, Ending Balance	26,539,300
Options Outstanding, Weighted Average Exercise Price, Beginning of Period	$ 32.48
Options Granted, Weighted Average Exercise Price	$ 38.13
Options Exercised, Weighted Average Exercise Price	$ 31.44
Options Cancelled, Weighted Average Exercise Price	$ 33.43
Options Outstanding, Weighted Average Exercise Price, End of Period	$ 33.88
Options Exercisable, Weighted Average Exercise Price, End of Period	$ 33.54