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Significant Accounting Policies - Schedule of Estimated Useful Lives of Property, Plant and Equipment (Detail) - Rocket Lab USA, Inc.
12 Months Ended
Dec. 31, 2020
Leasehold Improvements [Member]  
Property, Plant and Equipment [Line Items]  
Estimated useful life Shorter of remaining lease term or estimated useful life
Minimum [Member] | Buildings and Improvements [Member]  
Property, Plant and Equipment [Line Items]  
Estimated useful life 15 years
Minimum [Member] | Machinery, Equipment, Vehicles And Office Furniture [Member]  
Property, Plant and Equipment [Line Items]  
Estimated useful life 2 years
Minimum [Member] | Computer Equipment, Hardware and Software [Member]  
Property, Plant and Equipment [Line Items]  
Estimated useful life 3 years
Minimum [Member] | Launch Site Assets [Member]  
Property, Plant and Equipment [Line Items]  
Estimated useful life 3 years
Maximum [Member] | Buildings and Improvements [Member]  
Property, Plant and Equipment [Line Items]  
Estimated useful life 30 years
Maximum [Member] | Machinery, Equipment, Vehicles And Office Furniture [Member]  
Property, Plant and Equipment [Line Items]  
Estimated useful life 12 years
Maximum [Member] | Computer Equipment, Hardware and Software [Member]  
Property, Plant and Equipment [Line Items]  
Estimated useful life 5 years
Maximum [Member] | Launch Site Assets [Member]  
Property, Plant and Equipment [Line Items]  
Estimated useful life 10 years