| Cover | 6 Months Ended | |
| Nov. 08, 2023 | Sep. 30, 2023 | |
| Cover [Abstract] | ||
| Document Type | 6-K | |
| Entity Central Index Key | 0001973239 | |
| Document Fiscal Year Focus | 2024 | |
| Document Period End Date | Nov. 08, 2023 | |
| Amendment Flag | false | |
| Entity Registrant Name | ARM HOLDINGS PLC /UK | |
| Document Fiscal Period Focus | Q2 | |
| Current Fiscal Year End Date | --03-31 |
