Significant Accounting Policies (Policies)	9 Months Ended
Oct. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation As used in these financial statements, the term “Company” or “G-III” refers to G-III Apparel Group, Ltd. and its subsidiaries. The Company designs, manufactures and markets an extensive range of apparel, including outerwear, dresses, sportswear, swimwear, women’s suits and women’s performance wear, as well as women’s handbags, footwear, small leather goods, cold weather accessories and luggage. The Company also operates retail stores and licenses its proprietary brands under several product categories. The Company consolidates the accounts of its wholly-owned and majority-owned subsidiaries. KL North America B.V. (“KLNA”) is a Dutch limited liability company that is a joint venture that is 49% owned by the Company. Karl Lagerfeld Holding B.V. (“KLH”), formerly known as Kingdom Holdings 1 B.V., is a Dutch limited liability company that is 19% owned by the Company. Fabco Holding B.V. (“Fabco”) is a Dutch limited liability company that is a joint venture that is 49% owned by the Company. These investments are accounted for using the equity method of accounting. All material intercompany balances and transactions have been eliminated. Vilebrequin International SA (“Vilebrequin”), a Swiss corporation that is wholly-owned by the Company, KLH and KLNA report results on a calendar year basis rather than on the January 31 fiscal year basis used by the Company. The Company’s retail stores report results on a 52/53-week fiscal year. The results for the three and nine-month periods ended October 31, 2017 are not necessarily indicative of the results expected for the entire fiscal year, given the recent acquisition and integration of Donna Karan International Inc.(“DKI”) and the seasonal nature of the Company’s business. The accompanying financial statements included herein are unaudited. All adjustments (consisting of only normal recurring adjustments) necessary for a fair presentation of the financial position, results of operations and cash flows for the interim period presented have been reflected. The accompanying financial statements should be read in conjunction with the financial statements and notes included in the Company’s Annual Report on Form 10-K for the fiscal year ended January 31, 2017 filed with the Securities and Exchange Commission (the “SEC”). The Company’s international subsidiaries use different functional currencies, which are the local selling currency. In accordance with the authoritative guidance, operating assets and liabilities of the Company’s foreign operations are translated from foreign currency into U.S. dollars at period-end rates, while income and expenses are translated at the weighted-average exchange rates for the period. The related translation adjustments are reflected as a foreign currency translation adjustment in accumulated other comprehensive loss within stockholders’ equity.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Guidance Issued Being Evaluated for Adoption In May 2017, the Financial Accounting Standard Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU 2017-09, “Compensation — Stock Compensation (Topic 718): Scope of Modification Accounting.” ASU 2017-09 provides clarification on when modification accounting should be used for changes to the terms or conditions of a share-based payment award. ASU 2017-09 does not change the accounting for modifications but clarifies that modification accounting guidance should only be applied if there is a change to the value, vesting conditions or award classification and would not be required if the changes are considered non-substantive. The amendments of ASU 2017-09 are effective for reporting periods beginning after December 15, 2017, with early adoption permitted. The adoption of ASU 2017-09 is not expected to have an impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, “Intangibles — Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” The purpose of ASU 2017-04 is to simplify the subsequent measurement of goodwill by removing the second step of the two-step impairment test. The amendment should be applied on a prospective basis. ASU 2017-04 is effective for fiscal years beginning after December 15, 2019, including interim periods within that year. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company does not expect ASU 2017-04 to have an impact on its consolidated financial statements. In January 2017, the FASB issued ASU 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business.” The purpose of ASU 2017-01 is to clarify the definition of a business to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. ASU 2017-01 is effective for fiscal years beginning after December 15, 2017, including interim periods within that year. The amendments in ASU 2017-01 should be applied prospectively on or after the effective date. Early adoption is permitted. The Company does not expect ASU 2017-01 to have an impact on its consolidated financial statements. In October 2016, the FASB issued ASU 2016-16, “Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory.” The update requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset upon transfer other than inventory, eliminating the current recognition exception. Prior to the update, GAAP prohibited the recognition of current and deferred income taxes for intra-entity asset transfers until the asset was sold to an outside party. The amendments in this update do not include new disclosure requirements; however, existing disclosure requirements might be applicable when accounting for the current and deferred income taxes for an intra-entity transfer of an asset other than inventory. For public business entities, the amendments in this update are effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those fiscal years. The Company does not expect ASU 2016-16 to have a material impact on its consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” which clarifies guidance with respect to the classification of eight specific cash flow issues. ASU 2016-15 was issued to reduce diversity in practice and prevent financial statement restatements. Cash flow issues include: debt prepayment or debt extinguishment costs, settlement of zero-coupon bonds, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies and bank-owned life insurance policies, distributions received from equity method investees, beneficial interests in securitization transactions and separately identifiable cash flows and application of the predominance principle. ASU 2016-15 is effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Under the provision, entities must apply the guidance retrospectively to all periods presented but may apply it prospectively if retrospective application would be impracticable. The Company does not believe that adoption of this new guidance will have a material effect on its condensed consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” The primary difference between the current requirement under GAAP and ASU 2016-02 is the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases. The FASB has continued to clarify this guidance and most recently issued ASU 2017-13 “Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments.” ASU 2016-02 requires that a lessee recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term (other than leases that meet the definition of a short-term lease). The liability will be equal to the present value of lease payments. The asset will be based on the liability, subject to adjustment, such as for initial direct costs. For income statement purposes, the FASB retained a dual model, requiring leases to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). Classification will be based on criteria that are for the most part similar to those applied in current lease accounting. ASU 2016-02 may be adopted using a modified retrospective transition, and provides for certain practical expedients. Transactions will require application of the new guidance at the beginning of the earliest comparative period presented. The guidance is effective for public entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently assessing the potential impact of ASU 2016-02 on its consolidated financial statements. Given the Company’s significant number of leases, the Company expects this standard will result in a significant increase to its long-term assets and liabilities but does not expect it to have a material impact on its statements of operations. The Company is required to adopt the new standard in the first quarter of fiscal 2020 and does not expect to early adopt this new standard. In January 2016, the FASB issued ASU 2016-01, “Financial Instruments — Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities.” This standard (i) modifies how entities measure equity investments and present changes in the fair value of financial liabilities, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iii) changes presentation and disclosure requirements and (iv) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity’s other deferred tax assets. ASU 2016-01 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early application is permitted. The Company does not expect that the adoption of this ASU will have a material impact on its statement of operations. In May 2014, the FASB issued ASU 2014-09, "Revenue from Contracts with Customers (Topic 606)." This update will replace the existing revenue recognition guidance in GAAP and requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The FASB has continued to clarify this guidance and has issued ASU 2017-13 “Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments”; ASU 2016-08, “Principal versus Agent Considerations (Reporting Revenue Gross versus Net)”; ASU 2016-10, “Identifying Performance Obligations and Licensing”; ASU 2016-12, “Narrow-Scope Improvements and Practical Expedients”; and ASU 2016-20, “Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers.” The amendments to ASU 2014-09 are intended to render more detailed implementation guidance with the expectation of reducing the degree of judgment necessary to comply with Topic 606. These new standards have the same effective date as ASU 2014-09 and will be effective for public entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (modified retrospective method). The Company has decided to adopt the pronouncement using a modified retrospective approach. The Company performed an analysis of its current revenue streams worldwide and identified potential changes that will result from the adoption of the new guidance. The Company is currently identifying and preparing to implement changes to its accounting processes and controls to support the new revenue recognition and disclosure requirements. The Company currently believes that the adoption of Topic 606 will primarily affect its wholesale operations segment in the timing of recognition of certain adjustments that are currently recorded in net sales. For example, the Company is currently recording markdowns and certain customer allowances when the liability is known or incurred. Under the new guidance, the Company will have to estimate a liability for future anticipated markdowns and allowances related to all shipments that have taken place. The Company also expects that reclassifications of certain operating expenses that are considered customer assistance, such as cooperative advertising, which aggregated approximately $26.0 million in fiscal 2017 and are currently recorded in selling, general and administrative expenses, will be recorded as an offset to net sales under the new guidance. The Company believes that the retail operations segment will not be materially impacted by the new guidance, as its retail stores do not currently offer significant loyalty programs to customers. Under the new standard, the transition adjustment as of February 1, 2018 to retained earnings is estimated to be between approximately $23 million and $30 million. This estimate may change as the Company continues the evaluation of the new guidance.

Significant Accounting Policies (Policies)

9 Months Ended

Oct. 31, 2017

As used in these financial statements, the term “Company” or “G-III” refers to G-III Apparel Group, Ltd. and its subsidiaries. The Company designs, manufactures and markets an extensive range of apparel, including outerwear, dresses, sportswear, swimwear, women’s suits and women’s performance wear, as well as women’s handbags, footwear, small leather goods, cold weather accessories and luggage. The Company also operates retail stores and licenses its proprietary brands under several product categories.

The Company consolidates the accounts of its wholly-owned and majority-owned subsidiaries. KL North America B.V. (“KLNA”) is a Dutch limited liability company that is a joint venture that is 49% owned by the Company. Karl Lagerfeld Holding B.V. (“KLH”), formerly known as Kingdom Holdings 1 B.V., is a Dutch limited liability company that is 19% owned by the Company. Fabco Holding B.V. (“Fabco”) is a Dutch limited liability company that is a joint venture that is 49% owned by the Company. These investments are accounted for using the equity method of accounting. All material intercompany balances and transactions have been eliminated. Vilebrequin International SA (“Vilebrequin”), a Swiss corporation that is wholly-owned by the Company, KLH and KLNA report results on a calendar year basis rather than on the January 31 fiscal year basis used by the Company. The Company’s retail stores report results on a 52/53-week fiscal year.

The results for the three and nine-month periods ended October 31, 2017 are not necessarily indicative of the results expected for the entire fiscal year, given the recent acquisition and integration of Donna Karan International Inc.(“DKI”) and the seasonal nature of the Company’s business. The accompanying financial statements included herein are unaudited. All adjustments (consisting of only normal recurring adjustments) necessary for a fair presentation of the financial position, results of operations and cash flows for the interim period presented have been reflected.

The accompanying financial statements should be read in conjunction with the financial statements and notes included in the Company’s Annual Report on Form 10-K for the fiscal year ended January 31, 2017 filed with the Securities and Exchange Commission (the “SEC”).

The Company’s international subsidiaries use different functional currencies, which are the local selling currency. In accordance with the authoritative guidance, operating assets and liabilities of the Company’s foreign operations are translated from foreign currency into U.S. dollars at period-end rates, while income and expenses are translated at the weighted-average exchange rates for the period. The related translation adjustments are reflected as a foreign currency translation adjustment in accumulated other comprehensive loss within stockholders’ equity.

Recent Accounting Pronouncements

Accounting Guidance Issued Being Evaluated for Adoption

In May 2017, the Financial Accounting Standard Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU 2017-09, “Compensation — Stock Compensation (Topic 718): Scope of Modification Accounting.” ASU 2017-09 provides clarification on when modification accounting should be used for changes to the terms or conditions of a share-based payment award. ASU 2017-09 does not change the accounting for modifications but clarifies that modification accounting guidance should only be applied if there is a change to the value, vesting conditions or award classification and would not be required if the changes are considered non-substantive. The amendments of ASU 2017-09 are effective for reporting periods beginning after December 15, 2017, with early adoption permitted. The adoption of ASU 2017-09 is not expected to have an impact on the Company’s consolidated financial statements.

In January 2017, the FASB issued ASU 2017-04, “Intangibles — Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” The purpose of ASU 2017-04 is to simplify the subsequent measurement of goodwill by removing the second step of the two-step impairment test. The amendment should be applied on a prospective basis. ASU 2017-04 is effective for fiscal years beginning after December 15, 2019, including interim periods within that year. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company does not expect ASU 2017-04 to have an impact on its consolidated financial statements.

In January 2017, the FASB issued ASU 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business.” The purpose of ASU 2017-01 is to clarify the definition of a business to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. ASU 2017-01 is effective for fiscal years beginning after December 15, 2017, including interim periods within that year. The amendments in ASU 2017-01 should be applied prospectively on or after the effective date. Early adoption is permitted. The Company does not expect ASU 2017-01 to have an impact on its consolidated financial statements.

In October 2016, the FASB issued ASU 2016-16, “Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory.” The update requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset upon transfer other than inventory, eliminating the current recognition exception. Prior to the update, GAAP prohibited the recognition of current and deferred income taxes for intra-entity asset transfers until the asset was sold to an outside party. The amendments in this update do not include new disclosure requirements; however, existing disclosure requirements might be applicable when accounting for the current and deferred income taxes for an intra-entity transfer of an asset other than inventory. For public business entities, the amendments in this update are effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those fiscal years. The Company does not expect ASU 2016-16 to have a material impact on its consolidated financial statements.

In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” which clarifies guidance with respect to the classification of eight specific cash flow issues. ASU 2016-15 was issued to reduce diversity in practice and prevent financial statement restatements. Cash flow issues include: debt prepayment or debt extinguishment costs, settlement of zero-coupon bonds, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies and bank-owned life insurance policies, distributions received from equity method investees, beneficial interests in securitization transactions and separately identifiable cash flows and application of the predominance principle. ASU 2016-15 is effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Under the provision, entities must apply the guidance retrospectively to all periods presented but may apply it prospectively if retrospective application would be impracticable. The Company does not believe that adoption of this new guidance will have a material effect on its condensed consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” The primary difference between the current requirement under GAAP and ASU 2016-02 is the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases. The FASB has continued to clarify this guidance and most recently issued ASU 2017-13 “Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments.” ASU 2016-02 requires that a lessee recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term (other than leases that meet the definition of a short-term lease). The liability will be equal to the present value of lease payments. The asset will be based on the liability, subject to adjustment, such as for initial direct costs. For income statement purposes, the FASB retained a dual model, requiring leases to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). Classification will be based on criteria that are for the most part similar to those applied in current lease accounting. ASU 2016-02 may be adopted using a modified retrospective transition, and provides for certain practical expedients. Transactions will require application of the new guidance at the beginning of the earliest comparative period presented. The guidance is effective for public entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently assessing the potential impact of ASU 2016-02 on its consolidated financial statements. Given the Company’s significant number of leases, the Company expects this standard will result in a significant increase to its long-term assets and liabilities but does not expect it to have a material impact on its statements of operations. The Company is required to adopt the new standard in the first quarter of fiscal 2020 and does not expect to early adopt this new standard.

In January 2016, the FASB issued ASU 2016-01, “Financial Instruments — Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities.” This standard (i) modifies how entities measure equity investments and present changes in the fair value of financial liabilities, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iii) changes presentation and disclosure requirements and (iv) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity’s other deferred tax assets. ASU 2016-01 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early application is permitted. The Company does not expect that the adoption of this ASU will have a material impact on its statement of operations.

In May 2014, the FASB issued ASU 2014-09, "Revenue from Contracts with Customers (Topic 606)." This update will replace the existing revenue recognition guidance in GAAP and requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The FASB has continued to clarify this guidance and has issued ASU 2017-13 “Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments”; ASU 2016-08, “Principal versus Agent Considerations (Reporting Revenue Gross versus Net)”; ASU 2016-10, “Identifying Performance Obligations and Licensing”; ASU 2016-12, “Narrow-Scope Improvements and Practical Expedients”; and ASU 2016-20, “Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers.” The amendments to ASU 2014-09 are intended to render more detailed implementation guidance with the expectation of reducing the degree of judgment necessary to comply with Topic 606. These new standards have the same effective date as ASU 2014-09 and will be effective for public entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (modified retrospective method). The Company has decided to adopt the pronouncement using a modified retrospective approach. The Company performed an analysis of its current revenue streams worldwide and identified potential changes that will result from the adoption of the new guidance. The Company is currently identifying and preparing to implement changes to its accounting processes and controls to support the new revenue recognition and disclosure requirements. The Company currently believes that the adoption of Topic 606 will primarily affect its wholesale operations segment in the timing of recognition of certain adjustments that are currently recorded in net sales. For example, the Company is currently recording markdowns and certain customer allowances when the liability is known or incurred. Under the new guidance, the Company will have to estimate a liability for future anticipated markdowns and allowances related to all shipments that have taken place. The Company also expects that reclassifications of certain operating expenses that are considered customer assistance, such as cooperative advertising, which aggregated approximately $26.0 million in fiscal 2017 and are currently recorded in selling, general and administrative expenses, will be recorded as an offset to net sales under the new guidance. The Company believes that the retail operations segment will not be materially impacted by the new guidance, as its retail stores do not currently offer significant loyalty programs to customers. Under the new standard, the transition adjustment as of February 1, 2018 to retained earnings is estimated to be between approximately $23 million and $30 million. This estimate may change as the Company continues the evaluation of the new guidance.