Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Schedule of Assumptions (Details)

v3.19.1
Stock-Based Compensation Schedule of Assumptions (Details)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected life of options (in years)   4 years 273 days 4 years 273 days
Minimum risk free interest rate 2.60% 1.70% 1.10%
Maximum risk free interest rate 2.90% 2.00% 1.40%
Expected minimum volatility rate 69.60% 64.20% 57.40%
Expected maximum volatility rate 70.50% 66.20% 63.70%
Expected dividend yield 0.00% 0.00% 0.00%
Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected life of options (in years) 4 years 197 days    
Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected life of options (in years) 4 years 273 days