Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation (Details 2)

v2.4.0.8
Stock-Based Compensation (Details 2) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Summary of weighted average assumptions used to value options granted      
Grant date fair value of options (in dollars per share) $ 6.11 $ 4.96 $ 5.14
Volatility (as a percent) 40.40% 39.70% 39.40%
Risk-free interest rate (as a percent) 1.00% 1.20% 2.37%
Dividend yield (as a percent) 0.00% 0.00% 0.00%
Expected term 6 years 6 years 6 years