Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Assumptions Applied to Estimate Fair Value of Stock Option Awards (Details)

v3.19.3.a.u2
Stockholders' Equity - Assumptions Applied to Estimate Fair Value of Stock Option Awards (Details) - Stock options
12 Months Ended
Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Risk free interest rate, Minimum 1.65%
Risk free interest rate, Maximum 1.73%
Expected dividend yield 0.00%
Volatility, Minimum 41.61%
Volatility, Maximum 42.15%
Minimum  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Expected term (years) 3 years 6 months 14 days
Maximum  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Expected term (years) 4 years