Annual report pursuant to Section 13 and 15(d)

Stock Compensation - Valuation Assumptions (Details)

v3.3.1.900
Stock Compensation - Valuation Assumptions (Details)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend rate (as a percent) 0.00% 0.00% 0.00%
Expected term (in years) 4 years 9 months 4 years 9 months  
Expected volatility, minimum (as a percent) 36.00% 35.90% 35.90%
Expected volatility, maximum (as a percent) 36.20% 36.00% 41.40%
Risk-free rate of return. minimum (as a percent) 1.40%   0.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate   1.50%  
Risk-free rate of return, maximum (as a percent) 1.70%   1.40%
Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years)     4 years 7 months 7 days
Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years)     6 years 10 months 25 days