Basis of Presentation (Policies)	9 Months Ended
Oct. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The unaudited condensed consolidated financial statements of Marvell Technology Group Ltd., a Bermuda exempted company, and its wholly owned subsidiaries (the “Company”), as of and for the three and nine months ended October 31, 2020, have been prepared as required by the U.S. Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted as permitted by the SEC.
Fiscal Period	The Company’s fiscal year is the 52- or 53-week period ending on the Saturday closest to January 31. Accordingly, every fifth or sixth fiscal year will have a 53-week period. The additional week in a 53-week year is added to the fourth quarter, making such quarter consist of 14 weeks. Fiscal 2020 had a 52-week year. Fiscal 2021 is a 52-week year. On October 29, 2020, the Company entered into a merger agreement (the “Merger Agreement”) with Inphi Corporation (“Inphi”), whereby the Company will pay Inphi's stockholders $66 per share in cash and 2.323 common shares for each Inphi share, which represents purchase consideration of approximately $10 billion. The Company intends to fund the cash consideration with $4.0 billion in debt financing, and has obtained commitments consisting of a $2.5 billion bridge loan commitment, a $750 million 3-year term loan facility commitment and a $750 million 5-year term loan facility commitment from JP Morgan Chase Bank, N.A., in each case subject to customary terms and conditions. The transaction is not subject to any financing condition. The Company has recorded $22.3 million of associated deferred debt financing costs, with $11.2 million recorded in prepaid expenses and other current assets and $11.1 million recorded in other non-current assets on the accompanying unaudited condensed consolidated balance sheet as of October 31, 2020. The transaction is expected to close in the second half of calendar 2021, pending approval by Inphi's and the Company's stockholders, as well as regulatory approval and satisfaction of other customary closing conditions. As a result of the transaction, the parent company will be domiciled in the United States upon closing of the transaction. For periods after closing, the combined company will be subject to taxation in the United States, which may adversely impact the Company's future effective tax rates and tax liabilities. A fee of up to $460 million may be payable by the Company or $300 million payable by Inphi upon termination of the transaction, as more fully described in the Merger Agreement. If the Merger Agreement is terminated due to failure to obtain stockholder approval, the party whose stockholders did not approve the transaction will be obligated to reimburse the other party up to $25 million for its merger related fees and costs.
Use of Estimates	The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. On an ongoing basis, the Company evaluates its estimates, including those related to revenue recognition, provisions for sales returns and allowances, inventory excess and obsolescence, goodwill and other intangible assets, restructuring, income taxes, litigation and other contingencies. Actual results could differ from these estimates and such differences could affect the results of operations reported in future periods. In the current macroeconomic environment affected by COVID-19, these estimates require increased judgment and carry a higher degree of variability and volatility. As events continue to evolve and additional information becomes available, these estimates may change materially in future periods.
Accounting Pronouncements	Accounting Pronouncements Recently Adopted In June 2016, the Financial Accounting Standards Board (“FASB”) issued a new standard requiring financial assets measured at amortized cost be presented at the net amount expected to be collected, through an allowance for credit losses that is deducted from the amortized cost basis. The standard eliminates the probable initial recognition threshold and reflects an entity’s current estimate of all expected credit losses. The measurement of expected credit losses is based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the financial assets. The new standard was adopted by the Company on February 2, 2020 and did not have a material effect on the Company's consolidated financial statements. In August 2018, the FASB issued an accounting standards update to align the requirements for capitalizing implementation costs incurred in a software hosting arrangement that is a service contract and costs to develop or obtain internal-use software. The new standard was adopted by the Company on February 2, 2020 on a prospective basis and did not have a material effect on the Company's consolidated financial statements. In August 2018, the FASB issued an accounting standards update that modifies the disclosure requirements on fair value measurements. The new guidance adds, modifies and removes certain fair value measurement disclosure requirements. The new standard was adopted by the Company on February 2, 2020 and did not have a material effect on the Company's consolidated financial statements. In November 2018, the FASB issued an accounting standards update that clarifies when transactions between participants in a collaborative arrangement are within the scope of the new revenue recognition standard that the Company adopted at the beginning of fiscal 2019. The new standard was adopted by the Company on February 2, 2020 and did not have a material effect on the Company's consolidated financial statements. Accounting Pronouncements Not Yet Effective In December 2019, the FASB issued an accounting standards update that simplifies the accounting for income taxes by eliminating certain exceptions related to the approach for intraperiod tax allocation and modified the methodology for calculating income taxes in an interim period. It also clarifies and simplifies other aspects of the accounting for income taxes. The guidance is effective for the Company beginning in the first quarter of fiscal year 2022, with early adoption permitted. The Company does not expect the adoption of this guidance to have a material effect on its consolidated financial statements.

Basis of Presentation (Policies)

9 Months Ended

Oct. 31, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

The unaudited condensed consolidated financial statements of Marvell Technology Group Ltd., a Bermuda exempted company, and its wholly owned subsidiaries (the “Company”), as of and for the three and nine months ended October 31, 2020, have been prepared as required by the U.S. Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted as permitted by the SEC.

Fiscal Period

The Company’s fiscal year is the 52- or 53-week period ending on the Saturday closest to January 31. Accordingly, every fifth or sixth fiscal year will have a 53-week period. The additional week in a 53-week year is added to the fourth quarter, making such quarter consist of 14 weeks. Fiscal 2020 had a 52-week year. Fiscal 2021 is a 52-week year.

On October 29, 2020, the Company entered into a merger agreement (the “Merger Agreement”) with Inphi Corporation (“Inphi”), whereby the Company will pay Inphi's stockholders $66 per share in cash and 2.323 common shares for each Inphi share, which represents purchase consideration of approximately $10 billion. The Company intends to fund the cash consideration with $4.0 billion in debt financing, and has obtained commitments consisting of a $2.5 billion bridge loan commitment, a $750 million 3-year term loan facility commitment and a $750 million 5-year term loan facility commitment from JP Morgan Chase Bank, N.A., in each case subject to customary terms and conditions. The transaction is not subject to any financing condition. The Company has recorded $22.3 million of associated deferred debt financing costs, with $11.2 million recorded in prepaid expenses and other current assets and $11.1 million recorded in other non-current assets on the accompanying unaudited condensed consolidated balance sheet as of October 31, 2020.

The transaction is expected to close in the second half of calendar 2021, pending approval by Inphi's and the Company's stockholders, as well as regulatory approval and satisfaction of other customary closing conditions. As a result of the transaction, the parent company will be domiciled in the United States upon closing of the transaction. For periods after closing, the combined company will be subject to taxation in the United States, which may adversely impact the Company's future effective tax rates and tax liabilities. A fee of up to $460 million may be payable by the Company or $300 million payable by Inphi upon termination of the transaction, as more fully described in the Merger Agreement. If the Merger Agreement is terminated due to failure to obtain stockholder approval, the party whose stockholders did not approve the transaction will be obligated to reimburse the other party up to $25 million for its merger related fees and costs.

Use of Estimates

The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. On an ongoing basis, the Company evaluates its estimates, including those related to revenue recognition, provisions for sales returns and allowances, inventory excess and obsolescence, goodwill and other intangible assets, restructuring, income taxes, litigation and other contingencies. Actual results could differ from these estimates and such differences could affect the results of operations reported in future periods. In the current macroeconomic environment affected by COVID-19, these estimates require increased judgment and carry a higher degree of variability and volatility. As events continue to evolve and additional information becomes available, these estimates may change materially in future periods.

Accounting Pronouncements

Accounting Pronouncements Recently Adopted

In June 2016, the Financial Accounting Standards Board (“FASB”) issued a new standard requiring financial assets measured at amortized cost be presented at the net amount expected to be collected, through an allowance for credit losses that is deducted from the amortized cost basis. The standard eliminates the probable initial recognition threshold and reflects an entity’s current estimate of all expected credit losses. The measurement of expected credit losses is based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the financial assets. The new standard was adopted by the Company on February 2, 2020 and did not have a material effect on the Company's consolidated financial statements.

In August 2018, the FASB issued an accounting standards update to align the requirements for capitalizing implementation costs incurred in a software hosting arrangement that is a service contract and costs to develop or obtain internal-use software. The new standard was adopted by the Company on February 2, 2020 on a prospective basis and did not have a material effect on the Company's consolidated financial statements.

In August 2018, the FASB issued an accounting standards update that modifies the disclosure requirements on fair value measurements. The new guidance adds, modifies and removes certain fair value measurement disclosure requirements. The new standard was adopted by the Company on February 2, 2020 and did not have a material effect on the Company's consolidated financial statements.

In November 2018, the FASB issued an accounting standards update that clarifies when transactions between participants in a collaborative arrangement are within the scope of the new revenue recognition standard that the Company adopted at the beginning of fiscal 2019. The new standard was adopted by the Company on February 2, 2020 and did not have a material effect on the Company's consolidated financial statements.

Accounting Pronouncements Not Yet Effective

In December 2019, the FASB issued an accounting standards update that simplifies the accounting for income taxes by eliminating certain exceptions related to the approach for intraperiod tax allocation and modified the methodology for calculating income taxes in an interim period. It also clarifies and simplifies other aspects of the accounting for income taxes. The guidance is effective for the Company beginning in the first quarter of fiscal year 2022, with early adoption permitted. The Company does not expect the adoption of this guidance to have a material effect on its consolidated financial statements.