Registration of securities issued in business combination transactions

Collaboration Agreement - Additional Information (Detail)

v3.7.0.1
Collaboration Agreement - Additional Information (Detail) - USD ($)
 1 Months Ended 3 Months Ended 4 Months Ended 12 Months Ended 18 Months Ended
Apr. 24, 2015
Jan. 31, 2017
Aug. 31, 2016
Dec. 31, 2009
Mar. 31, 2017
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Apr. 24, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Jun. 30, 2016
May 14, 2015
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]                                  
Collaboration revenue recognized           $ 2,122,000 $ 2,940,000 $ 6,024,000 $ 6,737,000 $ 4,025,000 $ 1,374,000   $ 5,062,000 $ 18,160,000 $ 27,116,000    
Reversion rights period   90 days                              
Ionis Pharmaceuticals Inc. [Member]                                  
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]                                  
Litigation settlement, upfront payment     $ 1,400,000                            
Royalty payment percentage     5.00%                            
Sale, license or other transaction payment percentage     50.00%                            
Ionis Pharmaceuticals Inc. [Member] | Maximum [Member]                                  
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]                                  
Litigation settlement, success based payment     $ 5,000,000                            
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          
Collaboration revenue recognized                               $ 23,200,000  
Proceeds from advance reimbursement research and development, net amount       $ 50,000,000                          
Maximum cost exposure if third-party agreements discovered after the termination date         $ 100,000               $ 100,000        
Collaborative Arrangement [Member] | Ionis Pharmaceuticals Inc. [Member]                                  
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]                                  
Proceeds from advance reimbursement research and development, net amount $ 23,200,000                                
Hold-back amount, requested payment percentage                                 30.00%
Net proceed from collaboration agreement amount, requested payment percentage                                 20.00%