Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation (Narrative) (Details)

v3.20.4
Stock-Based Compensation (Narrative) (Details) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options $ 4,100,000 $ 9,900,000 $ 7,900,000
Stock-based compensation expense $ 17,778,000 17,832,000 14,291,000
2020 Plan [Member]      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Shares authorized 3,000,000.0    
Shares available for future grants 4,169,642    
Prior Plan [Member]      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Shares authorized 1,500,000    
Shares available for future grants 328,486    
Stock Options [Member]      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Stock-based compensation expense $ 7,000,000.0 6,200,000 4,900,000
Unrecognized costs related to share based compensation $ 11,500,000    
Weighted average period of recognition of unrecognized costs related to stock options, years 2 years 3 months 29 days    
Vesting period of options granted, years 4 years    
Expiration period, years 10 years    
Intrinsic value of stock options exercised $ 4,900,000 26,800,000 22,400,000
Cash received on exercises of stock options 6,900,000 19,800,000 18,500,000
Restricted Stock Units (RSUs) [Member]      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Stock-based compensation expense 10,800,000 $ 11,600,000 $ 9,400,000
Unrecognized costs related to share based compensation $ 18,600,000    
Weighted average period of recognition of unrecognized costs related to stock options, years 2 years 29 days    
Company withheld shares 54,543 56,843 55,907
Company withheld shares, tax obligations $ 4,500,000 $ 5,800,000 $ 4,300,000
Grant date fair value of vested units $ 11,000,000.0 $ 9,900,000 $ 7,900,000
Vesting period of options granted, years 4 years    
Restricted Stock Units (RSUs) [Member] | Minimum | After2009 [Member]      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Vesting period of options granted, years 2 years    
Restricted Stock Units (RSUs) [Member] | Maximum | After2009 [Member]      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Vesting period of options granted, years 3 years