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Stock Option Plans and Share-Based Compensation-Valuation Assumptions (Details)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Stock Options [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate 1.20% 0.90% 1.60%
Dividend yield 0.00% 0.00% 0.00%
Volatility 43.10% 45.80% 48.50%
Employee Stock Purchase Plan [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate 0.20% 0.20% 0.50%
Dividend yield 0.00% 0.00% 0.00%
Volatility 35.10% 38.50% 40.20%
Employee Stock Purchase Plan [Member] | Minimum [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term   6 months 6 months
Employee Stock Purchase Plan [Member] | Maximum [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term   2 years 2 years