v3.5.0.2
Document And Entity Information - shares
9 Months Ended
Sep. 30, 2016
Oct. 28, 2016
Document And Entity Information [Abstract]    
Entity Registrant Name Xenon Pharmaceuticals Inc.  
Document Type 10-Q  
Trading Symbol XENE  
Current Fiscal Year End Date --12-31  
Entity Common Stock, Shares Outstanding   17,893,304
Amendment Flag false  
Entity Central Index Key 0001582313  
Entity Filer Category Accelerated Filer  
Document Period End Date Sep. 30, 2016  
Document Fiscal Year Focus 2016  
Document Fiscal Period Focus Q3