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)
3 Months Ended 6 Months Ended
Jun. 25, 2018
shares
Jun. 30, 2018
USD ($)
ExecutiveOfficer
$ / shares
shares
Jun. 30, 2017
USD ($)
shares
Jun. 30, 2018
USD ($)
ExecutiveOfficer
$ / shares
shares
Jun. 30, 2017
USD ($)
shares
Dec. 31, 2017
USD ($)
shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Number of options granted       1,111,901    
Maximum number of shares issued upon exercise of incentive stock options   535,218   535,218    
Common stock, shares issued   19,108,221   19,108,221   948,578
Weighted average grant date fair value of options granted | $ / shares       $ 5.77    
Total intrinsic value of exercised stock options | $       $ 237,000    
Stock-based compensation expense recognized | $   $ 988,000 $ 38,000 $ 1,114,000 $ 76,000  
Early Exercise Stock Purchase Agreements            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Vesting period       36 months    
Nonvested common shares outstanding   101,823   101,823   45,224
Percentage of underlying option shares whose right to purchase lapses after applicable vesting commencement date       25.00%    
Right to repurchase shares underlying shares       0.0208    
Other Current Liabilities | Early Exercise Stock Purchase Agreements            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Shares issued upon early exercise of stock options are subject to repurchase | $   $ 158,000   $ 158,000   $ 18,000
Restricted Stock Units            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Number of RSU granted       10,189    
Weighted-average estimated grant-date fair value | $ / shares       $ 17.75    
Stock Options Granted to Employees that Contain Performance Condition            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Number of options granted   115,657   115,657    
Stock-based compensation expense recognized | $   $ 474,000   $ 474,000    
Number of executive officers granted with purchase option | ExecutiveOfficer   2   2    
Number of option vested 115,657          
Options vesting date       Jun. 25, 2018    
Stock-based compensation expense recognition period       2018-06    
Restricted Stock            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Vesting period       4 years    
Nonvested common shares outstanding   88,857   88,857   193,394
2018 Equity Incentive Plan            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Shares available for future issuance   1,812,145   1,812,145    
Number of shares will increase automatically through every year on specified date       --01-01    
Number of shares increase automatically continuing through maximum period       beginning on January 1, 2019 and continuing through and including January 1, 2028    
2018 Equity Incentive Plan | Common Stock            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Maximum number of shares available for issuance   1,600,692   1,600,692    
Increase in number of shares reserved for issuance as percentage of total number of shares of capital stock outstanding on last date of preceding calendar year       5.00%    
2018 Equity Incentive Plan | Common Stock | Non-Employee Director            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Maximum value of common stock to be granted during any calendar year inclusive of service fees | $       $ 750,000    
Maximum value of common stock to be granted during first year of appointment inclusive of service fees | $       $ 1,100,000    
2018 Equity Incentive Plan | Maximum [Member] | Common Stock            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Maximum number of shares available for issuance   4,000,000   4,000,000    
2018 Equity Incentive Plan | Employee options            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Number of options granted       75,621    
2018 Equity Incentive Plan | Restricted Stock Units            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Number of RSU granted   10,189 0 10,189 0  
Weighted-average estimated grant-date fair value | $ / shares   $ 17.75   $ 17.75    
Stock-based compensation expense recognized | $       $ 181,000    
2018 Equity Incentive Plan | Incentive Stock Options | Maximum [Member] | Common Stock            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Maximum number of shares issued upon exercise of incentive stock options   12,500,000   12,500,000    
2015 Equity Incentive Plan            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Vesting period       4 years    
Options to purchase of common stock outstanding   2,102,045   2,102,045    
Weighted average grant date fair value of options granted | $ / shares       $ 4.12    
Total intrinsic value of exercised stock options | $   $ 133,000   $ 237,000    
2015 Equity Incentive Plan | Maximum [Member]            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Options granted expiry period       10 years    
2018 Employee Stock Purchase Plan | Common Stock            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Shares available for future issuance   200,000   200,000    
Common stock, shares issued   0   0    
Common shares issued first offering period       0 years    
2018 Employee Stock Purchase Plan | Maximum [Member] | Common Stock            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Percentage of annual increase in number of common stock shares       1.00%    
Annual increase in number of common stock shares       375,000    
Option price per share of common stock at fair market value       85.00%