Share Based Compensation (Schedule Of Changes In The Number Of Shares Of Common Stock Under Option) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share Based Compensation [Abstract]
Shares, Outstanding, Beginning Balance	10,229	8,062	7,595
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 12.79	$ 7.45	$ 6.55
Options Exercisable at End of Year, Outstanding, Beginning Balance	5,168	5,523	4,375
Weighted Average Exercise Price of Exercisable Options, Outstanding, Beginning Balance	$ 6.06	$ 5.15	$ 3.82
Aggregate Intrinsic Value, Outstanding, Beginning Balance	$ 128,472	$ 70,958	$ 76,629
Shares, Granted	526	3,724	1,375
Weighted Average Exercise Price, Granted	$ 30.56	$ 22.56	$ 11.46
Weighted Average Fair Value of Options Granted During the Year, Granted	$ 9.72	$ 9.19	$ 2.96
Shares, Exercised	(2,008)	(143)	(215)
Weighted Average Exercise Price, Exercised	$ 4.51	$ 5.04	$ 1.23
Aggregate Intrinsic Value, Exercised	50,921	3,697	3,608
Shares, Forfeited	(406)	(729)	(693)
Weighted Average Exercise Price, Forfeited	$ 20.96	$ 11.95	$ 7.42
Shares, Tendered		(685)
Weighted Average Exercise Price, Tendered		$ 5.63
Shares, Outstanding, Ending Balance	8,341	10,229	8,062
Weighted Average Exercise Price, Outstanding, Ending balance	$ 15.51	$ 12.79	$ 7.45
Options Exercisable at End of Year, Outstanding, Ending Balance	4,394	5,168	5,523
Weighted Average Exercise Price of Exercisable Options, Outstanding, Ending Balance	$ 10.13	$ 6.06	$ 5.15
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 119,802	$ 128,472	$ 70,958
Shares, Vested and expected to vest	8,341
Weighted Average Exercise Price, Vested and expected to vest	$ 15.51