Stock Option Plan - Stock Option Activity (Parenthetical) (Details)	9 Months Ended
Sep. 30, 2015 shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options exercised for Number of Common Shares for cash	62,469
Common stock issued for cashless exercise	100,465
Cashless exercise of stock options	147,381

Number of common stock issued in exchange for share options (or share units) exercised via net exercise (cashless) method during the current period.

No definition available.

Name:	xene_CommonStockIssuedForCashlessExercise
Namespace Prefix:	xene_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration