Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation and Employee Benefit Plans - Additional Information (Details Textuals)

v3.10.0.1
Stock-Based Compensation and Employee Benefit Plans - Additional Information (Details Textuals) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Feb. 28, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term     2 years 10 months 30 days    
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options $ 5.5   $ 5.5    
Stock Issued During Period, Shares, Employee Stock Purchase Plans     151,840    
Employee Stock Purchase Plans, Weighted Average Purchase Price of Shares Purchased     $ 16.14    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value 0.1 $ 0.9 $ 4.0 $ 15.2  
Proceeds from Stock Options Exercised 0.1 1.1 1.3 7.1  
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options 1.2 $ 0.9 3.7 $ 11.2  
Shares Issued upon Settlement of Employee Bonus Plan         300,000
Accrued Bonuses $ 6.5   $ 6.5    
Equity Incentive Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 13,287,501   13,287,501    
ESPP [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 2,254,806   2,254,806    
Restricted Stock Unit and Restricted Stock Award [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized $ 60.6   $ 60.6    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term     2 years 8 months 35 days