Net Loss Per Share - Summary of Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Legacy Rocket Lab Preferred Stock [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equity shares	0	283,843,764
Legacy Rocket Lab Preferred Stock Warrants [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equity shares	0	1,123,959
Legacy Rocket Lab Common Stock Warrants [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equity shares	0	585,399
Stock Options And Restricted Stock Units [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equity shares	30,144,103	21,052,981