Stockholders' Equity (Summary Of Stock Option Activity) (Detail) (Stock Options [Member], USD $)	12 Months Ended
	Dec. 31, 2012
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Options outstanding at December 31, 2011	8,603,616
Number of Shares, Granted	1,785,656
Number of Shares, Exercised	(3,143,360)
Number of Shares, Forfeited	(207,621)
Number of Shares, Options outstanding at December 31, 2012	7,038,291
Number of Shares, Vested and exercisable at December 31, 2012	3,721,873
Weighted-Average Exercise Price, Options outstanding at December 31, 2011	$ 9.17
Weighted-Average Exercise Price, Granted	$ 44.43
Weighted-Average Exercise Price, Exercised	$ 7.01
Weighted-Average Exercise Price, Forfeited	$ 17.42
Weighted-Average Exercise Price, Options outstanding at December 31, 2012	$ 18.90
Weighted-Average Exercise Price, Vested and exercisable at December 31, 2012	$ 10.41
Weighted-Average Remaining Contractual Term (in years), Outstanding at December 31, 2012	7 years 3 months 11 days
Weighted-Average Remaining Contractual Term (in years), Vested and exercisable at December 31, 2012	5 years 10 months 17 days
Aggregate Intrinsic Value, Outstanding at December 31, 2012	$ 229.6	[1]
Aggregate Intrinsic Value, Vested and exercisable at December 31, 2012	$ 151.7	[1]
Closing stock price of common stock	$ 51.16

[1] The aggregate intrinsic value is calculated as the pre-tax difference between the weighted-average exercise price of the underlying awards and the closing price per share of $51.16 of the Company's common stock on December 31, 2012. The amount is presented in millions.