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

No definition available.

+ Details

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

- Definition

The number of shares issued by the entity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 106
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_NumberOfSharesIssued
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares that have been authorised and issued, reduced by treasury shares held. [Refer: Treasury shares]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 79
-Subparagraph a
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_79_a_iv&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_NumberOfSharesOutstanding
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares in the entity held by the entity or by its subsidiaries or associates. [Refer: Associates [member]; Subsidiaries [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 79
-Subparagraph a
-Clause vi
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_79_a_vi&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_SharesInEntityHeldByEntityOrByItsSubsidiariesOrAssociates
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	ifrs-full_ClassesOfShareCapitalAxis=gil_FirstPreferenceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfShareCapitalAxis=gil_SecondPreferencesSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

EQUITY (Share capital Narrative) (Details) - shares	Feb. 20, 2019	Jan. 31, 2019	Dec. 30, 2018	Dec. 31, 2017
Disclosure of classes of share capital [line items]
Shares issued (in shares)	206,740,357		206,732,436	219,198,989
Shares outstanding (in shares)		206,736,233	206,732,436	219,198,989
Number of shares in entity held by entity or by its subsidiaries or associates			3,797	4,308
First preferred shares
Disclosure of classes of share capital [line items]
Shares issued (in shares)			0	0
Second preferred shares
Disclosure of classes of share capital [line items]
Shares issued (in shares)			0	0