Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.7.0.1
Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Significant Accounting Policies [Line Items]          
Trade accounts receivable $ 0   $ 0   $ 110,000
Allowance for doubtful accounts 0   0    
Impairment of long-lived assets 0 $ 0 0 $ 0  
Fair value movements between Level 2 and Level 3 0 0 0 0  
Research and development expense 1,453,000 1,306,000 2,719,000 2,676,000  
Level 3 [Member]          
Significant Accounting Policies [Line Items]          
Financial instruments classified as Level 3 0 0 0 0  
Related-party In-licensing [Member]          
Significant Accounting Policies [Line Items]          
Research and development expense 21,000 9,000 27,000 23,000  
Third-party In-licensing [Member]          
Significant Accounting Policies [Line Items]          
Research and development expense $ 54,000 $ 30,000 $ 119,000 $ 339,000