Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Additional Information (Details)

v3.19.1
Stock-Based Compensation - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 12 Months Ended
Sep. 25, 2018
Jun. 08, 2018
Jun. 04, 2018
Sep. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Stock-based compensation         $ 14,728 $ 12,706  
Weighted Average Remaining Life (in years)         2 years 4 months 24 days    
IPO [Member] | PWERM [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Weighted average expected rate of return         80.00%    
Discount for lack of marketability         10.00%    
IPO [Member] | OPM [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Weighted average expected rate of return         20.00%    
Discount for lack of marketability         15.00%    
2018 Stock Compensation Plan [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Common stock reserved for issuance 1,632,134   3,300,000   1,522,354    
Maximum annual increase of outstanding stock reserved for future issuance, Percentage 5.00%            
Share based compensation awards expiration date       Jan. 31, 2020      
2018 Stock Compensation Plan [Member] | First Anniversary [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Stock options granted under the 2018 Plan vesting percentage         25.00%    
2018 Stock Compensation Plan [Member] | Second Anniversary [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Stock options granted under the 2018 Plan vesting percentage         25.00%    
2018 Stock Compensation Plan [Member] | Third Anniversary [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Stock options granted under the 2018 Plan vesting percentage         25.00%    
2018 Stock Compensation Plan [Member] | Forth Anniversary [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Stock options granted under the 2018 Plan vesting percentage         25.00%    
2018 Employee Stock Purchase Plan (ESPP) [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Maximum annual increase of outstanding stock reserved for future issuance, Percentage         1.25%    
Number of shares available for grant under the plan         296,752    
2014 Stock Option Plan [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Common stock reserved for issuance         1,000,000    
2014 Stock Option Plan [Member] | Maximum [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Stock option plan expiration period         10 years    
2003 Plan and 2014 Plan [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Time based awards vesting period         4 years    
Stock Options [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Stock-based compensation         $ 600 $ 700  
Unrecognized compensation expense for stock options issued         $ 14,200    
Weighted Average Remaining Life (in years)         9 years 5 months 4 days    
Weighted-average fair value of stock options granted         $ 12.70    
Stock Options [Member] | 2018 Stock Compensation Plan [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Authorized replacement equity awards of stock options and restricted stock units     1,901,900        
Replacement Awards [Member] | 2018 Stock Compensation Plan [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Authorized replacement equity awards of stock options and restricted stock units   1,340,832          
Unrecognized compensation cost of replacement awards         $ 17,200    
Share-based compensation arrangement by share-based payment award, Award vesting rights         generally vest 33% on the first anniversary of the grant date with the balance vesting monthly over the remaining two years    
Replacement Awards [Member] | 2018 Stock Compensation Plan [Member] | First Anniversary [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Stock options granted under the 2018 Plan vesting percentage       33.00%      
Restricted Stock Units (RSUs)              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Authorized replacement equity awards of stock options and restricted stock units         1,502,666    
Unrecognized compensation expense for stock options issued         $ 22,500    
Weighted Average Remaining Life (in years)         10 months 24 days    
Communicated Option Awards [Member]              
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]              
Weighted Average Remaining Life (in years)           4 years 10 months 9 days 5 years 18 days
Share based compensation liability     $ 18,200   $ 0 $ 15,400  
Weighted-average fair value of stock options granted         $ 12.91 $ 21.52