Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Additional Information (Details)

v3.10.0.1
Stock-Based Compensation - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 25, 2018
Jun. 08, 2018
Jun. 04, 2018
Sep. 30, 2018
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Stock-based compensation             $ 6,714 $ 11,528  
Weighted Average Remaining Life (in years)             2 years 8 months 12 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            
Maximum annual increase of outstanding stock reserved for future issuance, Percentage 5.00%                
Share based compensation awards expiration date             Jan. 31, 2020    
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       296,752 296,752   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 1,000,000   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         $ 100 $ 100 $ 400 $ 700  
Unrecognized compensation expense for stock options issued       $ 15,600 $ 15,600   $ 15,600    
Weighted Average Remaining Life (in years)             9 years 7 months 6 days    
Weighted-average fair value of stock options granted             $ 12.91    
Granted         0   1,901,900    
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 $ 17,200   $ 17,200    
Share-based compensation arrangement by share-based payment award, Award vesting rights             generally vest 33% at 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             1,340,832    
Unrecognized compensation expense for stock options issued       38,700 38,700   $ 38,700    
Communicated Option Awards [Member]                  
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                  
Weighted Average Remaining Life (in years)                 3 years 6 months 25 days
Share based compensation liability     $ 18,200 $ 0 $ 0   $ 0   $ 15,400
Weighted-average fair value of stock options granted           $ 18.57 $ 14.00 $ 8.15  
Granted           0 170,000