Stock Option Plan - Stock Option Activity (Parenthetical) (Details) - shares	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options exercised for Number of Common Shares for cash	16,246	26,910
Common stock issued for cashless exercise	0	14,032
Cashless exercise of stock options		17,746

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