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

No definition available.

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

- Definition

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

+ References

No definition available.

+ Details

Name:	giii_PercentageOfEmployerContributionToMatchParticipantContributionInDefinedContributionPlan
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_DefinedContributionPlanDisclosureLineItems
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

Name:	us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
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

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
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

Name:	us-gaap_BusinessAcquisitionAxis=giii_DonnaKaranInternationalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

EMPLOYEE BENEFIT PLANS (Detail Textuals) - USD ($)	1 Months Ended	12 Months Ended
EMPLOYEE BENEFIT PLANS (Detail Textuals) - USD ($)	Dec. 31, 2016	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Defined Contribution 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		$ 2,900,000	$ 2,300,000	$ 2,000,000
DKI
Defined Contribution Plan Disclosure [Line Items]
Percentage of employee's compensation matched by employer		7.00%
Employer matching percentage of employee contributions		50.00%
Defined contribution plan, matching contributions	$ 52,000
Maximum \| DKI
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, employee contribution percentage for which employer contributes a matching contribution		3.50%