Quarterly report pursuant to Section 13 or 15(d)

Intangibles - Additional Information (Detail)

v3.8.0.1
Intangibles - Additional Information (Detail) - USD ($)
3 Months Ended
Aug. 01, 2017
May 18, 2015
Mar. 31, 2018
Mar. 31, 2017
Finite Lived Intangible Assets [Line Items]        
Intangible assets, Fair Value $ 8,600,000 $ 3,100,000    
Intangible assets, Useful life 6 years 14 years    
License agreement amortization expense     $ 100,000 $ 100,000
Impairment of intangible assets     0  
Apatorsen License Agreements [Member]        
Finite Lived Intangible Assets [Line Items]        
Loss on disposition [note 4]     8,600,000  
Recovery of deferred income taxes [note 5]     $ 2,900,000