Related Parties (Details)	1 Months Ended
Mar. 31, 2018 shares
Teva [Member]
Related Party Transaction [Line Items]
Collaborative development and license agreement termination month and year	2018-03
Teva Canada Limited [Member]
Related Party Transaction [Line Items]
Number of common shares transferred and assigned for cancellation	1,000,000
Xenon Pharmaceuticals Inc [Member] \| Teva [Member] \| Minimum [Member]
Related Party Transaction [Line Items]
Percentage of ownership	5.00%
BVF Partners L.P [Member] \| Exchange Agreement [Member] \| Xenon Pharmaceuticals Inc [Member]
Related Party Transaction [Line Items]
Percentage of ownership	19.90%
BVF Partners L.P [Member] \| Exchange Agreement [Member] \| Series1 Preferred Shares
Related Party Transaction [Line Items]
Stock Issued	2,868,000
Common stock received and cancelled in exchange for preferred shares	2,868,000

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

No definition available.

Name:	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of new stock issued during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Collaborative development and license agreement termination month and year.

+ References

No definition available.

+ Details

Name:	xene_CollaborativeDevelopmentAndLicenseAgreementTerminationMonthAndYear
Namespace Prefix:	xene_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Common stock received and cancelled in exchange for preferred shares.

+ References

No definition available.

+ Details

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

- Definition

Number of common shares agreed to transfer and assign for cancellation.

+ References

No definition available.

+ Details

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

- Details

Name:	srt_CounterpartyNameAxis=xene_TevaPharmaceuticalsInternationalGmbHAndAffiliatedEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=xene_TevaCanadaLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=xene_XenonPharmaceuticalsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=xene_BVFPartnersLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=xene_ExchangeAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=xene_Series1PreferredSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: