| Document and Entity Information | Dec. 15, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | MARVELL TECHNOLOGY GROUP LTD |
| Amendment Flag | false |
| Entity Central Index Key | 0001058057 |
| Document Type | 8-K |
| Document Period End Date | Dec. 15, 2020 |
| Entity Incorporation State Country Code | D0 |
| Entity File Number | 0-30877 |
| Entity Tax Identification Number | 77-0481679 |
| Entity Address, Address Line One | Victoria Place |
| Entity Address, Address Line Two | 5th Floor |
| Entity Address, Address Line Three | 31 Victoria Street |
| Entity Address, City or Town | Hamilton |
| Entity Address, Postal Zip Code | HM 10 |
| Entity Address, Country | BM |
| City Area Code | (441) |
| Local Phone Number | 296-6395 |
| Written Communications | true |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Shares |
| Trading Symbol | MRVL |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
