FINANCIAL INSTRUMENTS (Financial expenses, net) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 29, 2024	Dec. 31, 2023
Financial Instruments [Abstract]
Interest expense on financial liabilities recorded at amortized cost	$ 80,256	$ 53,360
Bank and other financial charges	22,212	22,314
Interest accretion on discounted lease obligations	4,764	3,429
Interest accretion on discounted provisions	431	414
Foreign exchange (gain) loss	(3,509)	153
Financial expenses, net (note 14(c))	104,154	79,670
Borrowing costs recognised as expense	$ 0	$ 6,800
Capitalisation rate of borrowing costs eligible for capitalisation	0.00%	5.39%

Financial Instruments [Abstract]

No definition available.

Name:	gil_FinancialInstrumentsAbstract
Namespace Prefix:	gil_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Interest Accretion On Discounted Lease Obligations

+ References

No definition available.

+ Details

Name:	gil_InterestAccretionOnDiscountedLeaseObligations
Namespace Prefix:	gil_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of bank and similar charges recognised by the entity as an expense.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_112_c&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_BankAndSimilarCharges
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of interest and other costs that an entity incurs in connection with the borrowing of funds that are directly attributable to the acquisition, construction or production of a qualifying asset and which form part of the cost of that asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 23
-IssueDate 2024-01-01
-Paragraph 26
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=23&code=ifrs-tx-2024-en-r&anchor=para_26_a&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_BorrowingCostsCapitalised
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average of interest and other costs that an entity incurs in connection with the borrowing of funds applicable to the borrowings of the entity that are outstanding during the period, other than borrowings made specifically for the purpose of obtaining a qualifying asset. [Refer: Weighted average [member]; Borrowings]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 23
-IssueDate 2024-01-01
-Paragraph 26
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=23&code=ifrs-tx-2024-en-r&anchor=para_26_b&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_CapitalisationRateOfBorrowingCostsEligibleForCapitalisation
Namespace Prefix:	ifrs-full_
Data Type:	dtr-2022:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of expense recognised due to the unwinding of the discount on provisions other than provisions for employee benefits, resulting from the effect of the passage of time. [Refer: Other provisions]

+ References

+ Details

Name:	ifrs-full_ExpenseDueToUnwindingOfDiscountOnProvisions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of income or cost associated with interest and other financing activities of the entity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 85
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_85&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_FinanceIncomeCost
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of exchange differences recognised in profit or loss that arise from foreign currency transactions, excluding those arising on financial instruments measured at fair value through profit or loss in accordance with IFRS 9. [Refer: At fair value [member]; Classes of financial instruments [domain]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 21
-IssueDate 2024-01-01
-Paragraph 52
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=21&code=ifrs-tx-2024-en-r&anchor=para_52_a&doctype=Standard
-URIDate 2024-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 35
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_35&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationRecognisedInProfitOrLoss
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of interest expense for financial liabilities that are not at fair value through profit or loss. [Refer: At fair value [member]; Interest expense; Financial liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2024-01-01
-Paragraph 20
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2024-en-r&anchor=para_20_b&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_InterestExpenseForFinancialLiabilitiesNotAtFairValueThroughProfitOrLoss
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration