Share Based Compensation (Summary Of Changes In The Number Of Shares Of Common Stock Under Option) (Detail) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding, Beginning Balance	8,341
Shares, Granted	235
Shares, Exercised	(1,584)
Shares, Forfeited	(30)
Shares, Outstanding, Ending Balance	6,962
Shares, Expected to vest	6,962
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 15.51
Weighted Average Exercise Price, Granted	$ 40.65
Weighted Average Exercise Price, Exercised	$ 7.50
Weighted Average Exercise Price, Forfeited	$ 10.00
Weighted Average Exercise Price, Outstanding, Ending balance	$ 18.20
Weighted Average Exercise Price, Expected to vest	$ 18.20
Options Exercisable at End of Year, Outstanding, Ending Balance	3,339
Weighted Average Exercise Price of Exercisable Options, Outstanding, Beginning Balance	$ 10.13
Weighted Average Exercise Price of Exercisable Options, Outstanding, Ending Balance	$ 11.83
Outstanding at December 31, 2011	$ 119,802
Exercised	43,596
Outstanding at June 30, 2012	$ 117,228