Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies - Narrative (Details)

v3.19.1
Commitments and Contingencies - Narrative (Details)
3 Months Ended 12 Months Ended
Apr. 30, 2019
USD ($)
Feb. 19, 2019
USD ($)
Jan. 31, 2019
USD ($)
Sep. 25, 2018
USD ($)
Mar. 22, 2018
USD ($)
ft²
Dec. 04, 2017
USD ($)
Jan. 09, 2017
USD ($)
May 02, 2016
USD ($)
Mar. 31, 2019
USD ($)
employee
Dec. 31, 2018
USD ($)
Sep. 30, 2018
USD ($)
Jun. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
Dec. 31, 2015
USD ($)
Commitments and Contingencies [Line Items]                            
Lease cost                 $ 10,000.00          
Short-term Lease, Cost                 10,000.00          
Variable lease cost                 $ 5,000.000          
Minimum lease payments, year one                   $ 48,000        
Minimum lease payments, year two                   53,000        
Minimum lease payments, year three                   54,000        
Minimum lease payments, year four                   55,000        
Minimum lease payments, year five                   56,000        
Minimum lease payments, thereafter                   5,000        
Weighted average remaining term                 4 years 10 months 24 days          
Operating lease, weighted average discount rate (percent)                 9.60%          
Payments to HPI over three-year period               $ 750,000            
Payments for research and development agreement               $ 1,000,000.0       $ 1,000,000.0    
HPI out-licensing agreement term               3 years            
Research and development                 $ 2,932,000       $ 1,237,000  
Employee agreements, special termination benefits, number of employees | employee                 9          
Employee agreements, termination benefits provided to key employees, aggregate amount                 $ 1,200,000          
WPD Pharmaceuticals | First Two Years                            
Commitments and Contingencies [Line Items]                            
Research and development commitment   $ 2,000,000.0                        
WPD Pharmaceuticals | After Two Years                            
Commitments and Contingencies [Line Items]                            
Research and development commitment   1,000,000.0                        
MD Anderson                            
Commitments and Contingencies [Line Items]                            
Payments for research and development agreement                     $ 110,000      
MD Anderson | License                            
Commitments and Contingencies [Line Items]                            
Cost of services                 100,000       100,000  
Houston Pharmaceuticals, Inc. | Subsequent Event                            
Commitments and Contingencies [Line Items]                            
Option repurchase payment $ 1,000,000.0                          
Houston Pharmaceuticals, Inc. | License                            
Commitments and Contingencies [Line Items]                            
Cost of services                 100,000       100,000  
MD Anderson                            
Commitments and Contingencies [Line Items]                            
Payments for research and development agreement     $ 130,000 $ 400,000   $ 350,000 $ 300,000     $ 270,000     240,000  
Research and development                 100,000       $ 100,000  
Dermin                            
Commitments and Contingencies [Line Items]                            
Future payment to remove Germany                           $ 500,000
WPD Pharmaceuticals                            
Commitments and Contingencies [Line Items]                            
Future payment to remove Germany   $ 500,000                        
Lease Agreement For Corporate Office Space | IPX Memorial Drive Investors, LLC                            
Commitments and Contingencies [Line Items]                            
Leased office space (in square feet) | ft²         2,333                  
Term of operating lease (in months)         66 months                  
Operating lease, renewal term (in years)         5 years                  
Operating lease, monthly rent expense         $ 4,300                  
Operating lease, rent expense, annual increase in rent (as a percent)         3.00%                  
Maximum                            
Commitments and Contingencies [Line Items]                            
Payments for royalties                 600,000          
Maximum | MD Anderson                            
Commitments and Contingencies [Line Items]                            
License agreement, annual license fee                 100,000          
Milestone payments liabilities                 500,000          
Maximum | MD Anderson | Submission Of NDA And Receipt Of First Marketing Approval For Sale Of A Licensed Product                            
Commitments and Contingencies [Line Items]                            
Milestone payments liabilities                 $ 600,000