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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The amount of investments in joint ventures. [Refer: Joint ventures [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2017-01-01
-Paragraph 10
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=27&date=2017-03-01&anchor=para_10&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_InvestmentsInJointVentures
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The entity's share of the profit (loss) of joint ventures accounted for using the equity method. [Refer: Investments accounted for using equity method; Joint ventures [member]; Profit (loss)]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 85
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_85&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_ShareOfProfitLossOfJointVenturesAccountedForUsingEquityMethod
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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Contribution to joint venture.

No definition available.

Name:	lac_ContributionToJointVenture
Namespace Prefix:	lac_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Elimination of unrealized interest on loans to joint venture.

No definition available.

Name:	lac_EliminationOfUnrealizedInterestOnLoansToJointVenture
Namespace Prefix:	lac_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Investment in joint venture translation adjustment.

No definition available.