Stock-Based Compensation (Options Outstanding) (Detail) (USD $)	9 Months Ended
	Sep. 30, 2012
Shares Under Option, end of period	2,190,907
Exercised, Share Under Option	(1,090,998)
Shares Under Option, end of period	1,099,909	[1]
Weighted Average Exercise Price, beginning of period	$ 105.33
Exercised, Weighted Average Exercise Price	$ 42.39
Weighted Average Exercise Price, end of period	$ 167.76	[1]

[1] At September 30, 2012, all options were vested. The aggregate intrinsic value of options exercised during the nine months ended September 30, 2012 was $157 million.