Represents amount related to related party transaction, inventory sold to related party.

No definition available.

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

- Definition

Represents amount of expense related to royalty and advertising expense.

+ References

No definition available.

+ Details

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- Definition

Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

+ References

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Balance Type:	credit
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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-Publisher FASB
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Balance Type:	na
Period Type:	instant

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of asset related to consideration paid in advance for costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

+ References

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Balance Type:	debit
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

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Balance Type:	credit
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Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=giii_KarlLagerfeldNorthAmericaMember
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Balance Type:
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Name:	srt_OwnershipAxis=giii_KarlLagerfeldNorthAmericaMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=giii_FabcoMember
Namespace Prefix:
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Balance Type:
Period Type:

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Name:	srt_OwnershipAxis=giii_FabcoMember
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RELATED PARTY TRANSACTIONS - Textuals (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Related Party Transaction [Line Items]
Revenues	$ 754,617	$ 1,128,403	$ 643,892	$ 633,552	$ 766,785	$ 1,072,982	$ 624,698	$ 611,743	$ 3,160,464	$ 3,076,208	$ 2,806,938
KLNA
Related Party Transaction [Line Items]
Royalty and advertising expense									$ 6,800	6,400	$ 4,800
KLNA \| KLNA
Related Party Transaction [Line Items]
Percent of interest acquired in joint venture	49.00%								49.00%
Fabco
Related Party Transaction [Line Items]
Inventory sold to related party									$ 4,400
Revenues									3,100	$ 2,200
Prepaid expenses	$ 500								500
Due to related party	$ 100								$ 100
Fabco \| Fabco
Related Party Transaction [Line Items]
Percentage of ownership interest	49.00%								49.00%