IEEPA TARIFF REFUND (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jul. 31, 2026	Jul. 31, 2026	Apr. 30, 2026
IEEPA TARIFF REFUND
Tariff refund receivable	$ 9.8	$ 9.8	$ 139.5
Reduction in COGS, tariff expense		126.4
Reduction in inventory, tariff capitalized	13.6	$ 13.6
Tariff refund	129.7
Statutory interest received on tariff refund	$ 4.2

Amount of statutory interest received on tariff refund claims during the current period.

No definition available.

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Amount of tariff refund received from during the current period.

No definition available.

Name:	giii_ProceedsFromTariffRefunds
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of reduction in the carrying value of inventories related to tariffs previously capitalized as cost of inventory.

No definition available.

Name:	giii_TariffCapitalizedInventoryAdjustment
Namespace Prefix:	giii_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount recognized as a reduction in cost of goods sold representing tariff expense associated with inventory sold to customers during the period.

No definition available.

Name:	giii_TariffExpenseOnInventorySoldReductionInCostOfGoodsSold
Namespace Prefix:	giii_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Tariff refund receivable

No definition available.

Name:	giii_TariffRefundReceivableAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of receivable related to tariffs paid by the Company.

No definition available.

Name:	giii_TariffRefundReceivableAmount
Namespace Prefix:	giii_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant