Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Details 2)

v2.4.0.8
Stock-Based Compensation (Details 2) (USD $)
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Summary of weighted average assumptions used to value options granted    
Grant date fair value of options (in dollars per share) $ 16.81 $ 6.11
Volatility (as a percent) 38.70% 40.40%
Risk-free interest rate (as a percent) 1.80% 1.00%
Dividend yield (as a percent) 0.00% 0.00%
Expected term 6 years 6 years