Quarterly report pursuant to Section 13 or 15(d)

Merger Agreement with Molecular Templates - Additional Information (Detail)

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Merger Agreement with Molecular Templates - Additional Information (Detail) - USD ($)
Mar. 16, 2017
Mar. 24, 2017
Longitude    
Business Acquisition [Line Items]    
Commitment to purchase equity securities under equity commitment letter $ 20,000,000  
Amount of additional equity commitments to be secured for equity commitment letter $ 20,000,000  
Merger Agreement | Molecular Templates Inc    
Business Acquisition [Line Items]    
Molecular Templates equity holders ownership interest 65.60%  
Termination fee $ 800,000  
Merger Agreement | Molecular Templates Inc | Minimum    
Business Acquisition [Line Items]    
Amount of qualified financing contingent for repayment of promissory note 10,000,000  
Merger Agreement | Molecular Templates Inc | Notes    
Business Acquisition [Line Items]    
Aggregate principal amount $ 4,000,000  
Principal amount   $ 2,000,000