| Document and Entity Information | Dec. 22, 2021 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001819994 |
| Document Type | 8-K |
| Document Period End Date | Dec. 22, 2021 |
| Entity Registrant Name | Rocket Lab USA, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-39560 |
| Entity Tax Identification Number | 98-1550340 |
| Entity Address, Address Line One | 3881 McGowen Street |
| Entity Address, City or Town | Long Beach |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 90808 |
| City Area Code | (714) |
| Local Phone Number | 465-5737 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Common Stock 0.0001 Par Value Per Share [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Stock, $0.0001 par value per share |
| Trading Symbol | RKLB |
| Security Exchange Name | NASDAQ |
| Redeemable Warrants Each Whole Warrant Exercisable For One Share Of Common Stock 0.0001 Par Value [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Redeemable warrants, each whole warrant exercisable for one share of common stock, $0.0001 par value |
| Trading Symbol | RKLBW |
| Security Exchange Name | NASDAQ |
