Subsequent Events - Additional Information (Details) - USD ($)
 1 Months Ended 3 Months Ended 12 Months Ended
Mar. 29, 2018
Mar. 02, 2018
Jan. 01, 2018
Mar. 05, 2015
Sep. 30, 2017
May 31, 2017
Aug. 31, 2016
Mar. 31, 2016
Oct. 31, 2015
Mar. 31, 2015
Mar. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Apr. 25, 2018
Subsequent Event [Line Items]                              
Options granted                       264,480 2,918,993 4,309,232  
Exercise price of options                       $ 8.76 $ 1.53 $ 0.60  
Contractual term       10 years                      
Vesting period       5 years                      
Management and employees                              
Subsequent Event [Line Items]                              
Options granted         101,584 158,313 1,760,368 1,157,793 3,438,783 870,449          
Exercise price of options         $ 18.0 $ 3.0 $ 1.74 $ 1.2 $ 0.6 $ 0.6          
Contractual term         10 years 10 years 10 years 10 years 10 years 10 years          
Vesting period         5 years   5 years 5 years 5 years 5 years          
Management and employees | Minimum                              
Subsequent Event [Line Items]                              
Vesting period           4 years                  
Management and employees | Maximum                              
Subsequent Event [Line Items]                              
Vesting period           5 years                  
Management and employees | Vesting anniversary year after the grant date                              
Subsequent Event [Line Items]                              
Vesting percentage         20.00%   20.00% 20.00%              
Management and employees | Vesting anniversary year after the grant date | Minimum                              
Subsequent Event [Line Items]                              
Vesting percentage           25.00%                  
Management and employees | Vesting anniversary year after the grant date | Maximum                              
Subsequent Event [Line Items]                              
Vesting percentage           20.00%                  
Subsequent Event | Group and Hanmi                              
Subsequent Event [Line Items]                              
Paymet due from party $ 0                            
Accrued payment obligation $ 0                            
License and collaboration agreement termination date Mar. 29, 2018                            
Subsequent Event | Entasis Therapeutics Holdings Inc.                              
Subsequent Event [Line Items]                              
Non-refundable upfront fees obligated to pay                             $ 5,000,000
Subsequent Event | Each yearly anniversary from the date of the agreement | Restricted Shares                              
Subsequent Event [Line Items]                              
Vesting percentage   20.00%                          
Subsequent Event | Independent Directors | Restricted Shares                              
Subsequent Event [Line Items]                              
Shares granted     37,500                        
Subsequent Event | Certain Management | Restricted Shares                              
Subsequent Event [Line Items]                              
Shares granted   100,000                          
Subsequent Event | 2017 Plan | Management and employees                              
Subsequent Event [Line Items]                              
Options granted                     1,153,750        
Contractual term                     10 years        
Vesting period                     5 years        
Subsequent Event | 2017 Plan | Management and employees | Minimum                              
Subsequent Event [Line Items]                              
Exercise price of options                     $ 20.74        
Subsequent Event | 2017 Plan | Management and employees | Maximum                              
Subsequent Event [Line Items]                              
Exercise price of options                     $ 24.58        
Subsequent Event | 2017 Plan | Management and employees | Vesting anniversary year after the grant date                              
Subsequent Event [Line Items]                              
Vesting percentage                     20.00%