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Share-Based Compensation (Schedule Of Weighted Average Fair Value Assumptions Using Black-Scholes Option-Pricing Model) (Details) (USD $)
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Share-Based Compensation [Abstract]      
Expected dividend yield         
Range of risk free interest rate, minimum 1.40% 1.90% 1.60%
Range of risk free interest rate, maximum 2.90% 3.40% 3.40%
Weighted-average volatility 67.80% 71.40% 77.20%
Range of volatility, minimum 62.30% 69.30% 71.50%
Range of volatility, maximum 69.30% 72.40% 79.90%
Range of expected option life, minimum (in years) 5.50 5.50 5.50
Range of expected option life, maximum (in years) 6.25