Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Summary of Restricted Stock Unit Award Activity (Detail)

v3.8.0.1
Common Stock - Summary of Restricted Stock Unit Award Activity (Detail) - Restricted Stock Unit [Member]
9 Months Ended
Sep. 30, 2017
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of Shares, Additions from OncoGenex Plans | shares 10,543
Number of Shares, Granted | shares 205,100
Number of Shares, Released | shares (5,208)
Number of Shares, Forfeited or expired | shares (19)
Number of Shares, Ending Balance | shares 210,416
Weighted-Average Grant Date Fair Value, Additions from OncoGenex Plans | $ / shares $ 41.14
Weighted-Average Grant Date Fair Value, Granted | $ / shares 2.89
Weighted-Average Grant Date Fair Value, Released | $ / shares 44.36
Weighted-Average Grant Date Fair Value, Forfeited or expired | $ / shares 51.91
Weighted-Average Grant Date Fair Value, Ending Balance | $ / shares $ 3.78