EMPLOYEE BENEFIT PLANS (Detail Textuals) - USD ($) $ in Millions	12 Months Ended
Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Non-discretionary matching contribution			100.00%
Percentage of employee's compensation matched by employer			3.00%
Employer matching percentage of employee contributions			50.00%
Percentage of additional employee's compensation matched by employer			2.00%
Defined contribution plan, matching contributions	$ 2.3	$ 2.0	$ 1.3
Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employee contribution percentage for which employer contributes a matching contribution			6.00%

Represents defined contribution plan additional maximum annual contributions per employee percent.

No definition available.

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Namespace Prefix:	giii_
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Period Type:	duration

- Definition

Percentage Of Employer Contribution To Match Participant Contribution In Defined Contribution Plan

+ References

No definition available.

+ Details

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Namespace Prefix:	giii_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
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Period Type: