Stockholders' Equity (Summary Of Stock Option Activity) (Details) (Stock Option [Member], USD $)	3 Months Ended
	Mar. 31, 2012
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at December 31, 2011	4,301,808
Number of Options, Granted	251,378
Number of Options, Exercised	(477,858)
Number of Options, Forfeited	(26,088)
Outstanding at March 31, 2012	4,049,240
Weighted Average Exercise Price, Outstanding at December 31, 2011	$ 18.34
Weighted Average Exercise Price, Granted	$ 57.92
Weighted Average Exercise Price, Exercised	$ 14.22
Weighted Average Exercise Price, Forfeited	$ 26.19
Weighted Average Exercise Price, Outstanding at March 31, 2012	$ 21.24
Weighted Average Remaining Contractual Term (in years), Outstanding at March 31, 2012	$ 6.99
Aggregate Intrinsic Value, Outstanding at March 31, 2012	$ 216.6	[1]
Number of Options, Vested and exercisable at March 31, 2012	2,427,021
Weighted Average Exercise Price, Vested and exercisable at March 31, 2012	$ 17.52
Weighted Average Remaining Contractual Term (in years), Vested and exercisable at March 31, 2012	$ 5.80
Aggregate Intrinsic Value, Vested and exercisable at March 31, 2012	$ 138.8	[1]
Closing stock price of common stock	$ 74.72

[1] The aggregate intrinsic value is calculated as the pre-tax difference between the exercise price of the underlying awards and the closing stock price per share of $74.72 of the Company's common stock on March 30, 2012. The amount is presented in millions.