Share Capital - Stock Option Activity (Parenthetical) (Details) - shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options exercised for Number of Common Shares for cash	63,425	47,413
Common stock issued for cashless exercise	4,405	47,841
Cashless exercise of stock options	7,581	73,879

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