Stock-Based Compensation (Schedule Of Black-Scholes Assumptions Used For Stock Options) (Detail) (Stock Option [Member], USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011		Jun. 30, 2012	Jun. 30, 2011
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Risk-free interest rate, minimum	0.83%			0.83%	2.33%
Risk-free interest rate, maximum				1.01%	2.34%
Estimated volatility, minimum	71.00%			71.00%	81.00%
Estimated volatility, maximum				73.00%
Estimated dividend yield			[1]
Weighted-average grant date fair value per share of options granted	$ 51.73			$ 40.91	$ 11.07
Minimum [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Estimated term (in years), maximum	5 years 5 months 1 day			5 years 5 months 1 day	5 years 11 months 27 days
Maximum [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Estimated term (in years), maximum				5 years 5 months 23 days

[1] No stock options were granted during the three months ended June 30, 2011.