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Share-Based Compensation (Details 3) (USD $)
12 Months Ended
Dec. 31, 2011
Y
Dec. 31, 2010
Y
Dec. 31, 2009
Y
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Weighted average fair value $ 6.98 $ 10.74 $ 7.99
Expected volatility 41.85% 47.50% 47.46%
Expected life (years) 6.50 6.50 6.47
Risk-free interest rate 2.58% 2.87% 2.81%
Dividend yield 0.00% 0.00% 0.00%