Quarterly report pursuant to Section 13 or 15(d)

Collaboration Agreement - Additional Information (Detail)

v3.4.0.3
Collaboration Agreement - Additional Information (Detail) - USD ($)
 1 Months Ended 3 Months Ended 4 Months Ended
Apr. 24, 2015
Dec. 31, 2009
Mar. 31, 2016
Mar. 31, 2015
Apr. 24, 2015
Dec. 31, 2015
May. 14, 2015
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]              
Collaboration revenue     $ 2,940,000 $ 1,374,000      
Balance in advanced reimbursement payment recorded in deferred collaboration revenue     2,099,000     $ 5,040,000  
Collaborative Arrangement [Member] | Teva Pharmaceutical Industries Ltd. [Member]              
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]              
Proceeds from advance reimbursement research and development         $ 27,000,000    
Hold-back amount and third-party expenses deducted from advanced reimbursement payment $ 3,800,000       3,800,000    
Hold-back amount deducted from advanced reimbursement payment 3,000,000       3,000,000    
Third-party expenses deducted from advanced reimbursement payment         $ 800,000    
Maximum cost exposure if third-party agreements discovered after the termination date     100,000        
Proceeds from advance reimbursement research and development, net amount   $ 50,000,000          
Collaborative Arrangement [Member] | Ionis Pharmaceuticals Inc. and University of British Columbia [Member]              
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]              
Milestone payment due     $ 20,000,000        
Period of milestone payment     21 days        
Reserve for contingency of non payment of non-royalty milestone amount     $ 20,000,000        
Milestone payment made     10,000,000        
Balance amount of milestone payment     $ 10,000,000        
Collaborative Arrangement [Member] | Ionis Pharmaceuticals Inc. and University of British Columbia [Member] | Minimum [Member]              
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]              
Percentage of net sales required to be paid as royalty to third party     4.00%        
Collaborative Arrangement [Member] | Ionis Pharmaceuticals Inc. and University of British Columbia [Member] | Maximum [Member]              
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]              
Percentage of net sales required to be paid as royalty to third party     8.00%        
Collaborative Arrangement [Member] | Ionis Pharmaceuticals Inc. [Member]              
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]              
Net proceed from collaboration agreement amount, requested payment percentage             20.00%
Proceeds from advance reimbursement research and development, net amount $ 23,200,000            
Hold-back amount, requested payment percentage             30.00%
Amount due to Ionis for reimbursement for research and development activities     $ 0        
Milestone payment due     $ 20,000,000        
Period of milestone payment     21 days        
Reserve for contingency of non payment of non-royalty milestone amount     $ 20,000,000        
Milestone payment made     10,000,000        
Balance amount of milestone payment     10,000,000        
Collaborative Arrangement [Member] | Ionis Pharmaceuticals Inc. [Member] | Minimum [Member]              
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]              
Damages arise due to termination of agreement     $ 10,000,000