| Document and Entity Information | Nov. 04, 2019 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001058057 |
| Document Type | 8-K |
| Document Period End Date | Nov. 4, 2019 |
| Entity Registrant Name | MARVELL TECHNOLOGY GROUP LTD. |
| Entity Incorporation, State or Country Code | D0 |
| Entity File Number | 000-30877 |
| Entity Tax Identification Number | 77-0481679 |
| Entity Address, Address Line One | Canon’s Court |
| Entity Address, Address Line Two | 22 Victoria Street |
| Entity Address, City or Town | Hamilton |
| Entity Address, Postal Zip Code | HM 12 |
| Entity Address, Country | BM |
| City Area Code | 441 |
| Local Phone Number | 296-6395 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Shares |
| Trading Symbol | MRVL |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
