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 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 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     1 year 7 months 24 days    
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options $ 4.2   $ 4.2    
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 1.8 $ 12.4 $ 3.9 $ 14.3  
Proceeds from Stock Options Exercised 0.2 5.6 1.2 6.0  
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options 0.4 $ 9.9 2.5 $ 10.3  
Shares Issued upon Settlement of Employee Bonus Plan         300,000
Accrued Bonuses $ 4.0   $ 4.0    
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 13,579,573   13,579,573    
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 $ 63.6   $ 63.6    
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 5 days    
Employee Stock Option [Member]          
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 21 days    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross     0