Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity Stock Options and Net Income per Share - Employee Stock Purchase Plan (Details)

v3.19.3.a.u2
Shareholders' Equity Stock Options and Net Income per Share - Employee Stock Purchase Plan (Details)
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2019
USD ($)
$ / shares
shares
Dec. 31, 2018
USD ($)
$ / shares
shares
Dec. 31, 2017
USD ($)
$ / shares
shares
Schedule of Employee Stock Purchase Plan (ESPP) Disclosures [Line Items]      
Share-based compensation | $ $ 11,907 $ 10,549 $ 8,103
Employee Stock Purchase Plan [Member]      
Schedule of Employee Stock Purchase Plan (ESPP) Disclosures [Line Items]      
Number of shares authorized under the plan | shares 350    
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date 90.00%    
Number Of Large Lump Sum Contributions Related To Essp Stock Purchases 2    
Purchase Period for Employee Stock Purchase Plan 6 months    
Common stock issued under employee stock purchase plan (in shares) | shares 12 9 10
Weighted average price of shares purchased (dollars per share) | $ / shares $ 51 $ 51 $ 46
Weighted Average Grant Date Fair Value | $ / shares $ 14 $ 6 $ 9
Share-based compensation | $ $ 163 $ 59 $ 92