Quarterly report pursuant to Section 13 or 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 3 Months Ended 12 Months Ended
Sep. 25, 2018
Jun. 04, 2018
May 17, 2018
Sep. 30, 2018
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Dec. 31, 2017
Jun. 08, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Stock-based compensation         $ 7,745 $ 524      
Weighted Average Remaining Life (in years)         2 years 1 month 6 days        
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     2,146,061        
Maximum annual increase of outstanding stock reserved for future issuance, Percentage 5.00%                
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         455,367        
2014 Stock Option Plan [Member]                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Common stock reserved for issuance     1,000,000            
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         $ 500 $ 100      
Unrecognized compensation expense for stock options issued         $ 12,600        
Weighted Average Remaining Life (in years)         9 years 2 months 8 days   9 years 5 months 4 days    
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              
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              
Share based compensation awards expiration date       Jan. 31, 2020          
Stock Options [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% 25.00%        
Stock Options [Member] | 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%        
Stock Options [Member] | 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%        
Stock Options [Member] | 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%        
Restricted Stock Units (RSUs) [Member]                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Unrecognized compensation expense for stock options issued         $ 16,400        
Weighted-average recognized period         10 months 24 days        
Restricted Stock Units (RSUs) [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              
Communicated Option Awards [Member]                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Weighted Average Remaining Life (in years)           4 years 8 months 15 days   3 years 6 months 25 days  
Share based compensation liability           $ 15,900      
Weighted-average fair value of stock options granted           $ 12.53      
Maximum [Member] | 2014 Stock Option Plan [Member]                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Stock option plan expiration period     10 years