Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation and Employee Benefit Plans - ESPP (Details)

v3.10.0.1
Stock-Based Compensation and Employee Benefit Plans - ESPP (Details) - $ / shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
ESPP [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock Issued During Period, Shares, Employee Stock Purchase Plans 275,782    
Share-based Compensation Arrangement by Share-based Payment Award, Per Share Weighted Average Price of Shares Purchased $ 16.14    
Employee Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield 0.00% 0.00% 0.00%
Expected life (in years) 6 months   6 months
Minimum [Member] | Employee Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted-average grant date fair value per share $ 5.01 $ 6.20 $ 5.85
Risk-free interest rate 2.00% 0.60% 0.38%
Expected life (in years)   4 months 17 days  
Volatility 38.82% 29.56% 49.94%
Maximum [Member] | Employee Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted-average grant date fair value per share $ 5.37 $ 7.46 $ 6.20
Risk-free interest rate 2.51% 1.40% 0.60%
Expected life (in years)   6 months  
Volatility 46.17% 49.94% 53.94%