Annual report pursuant to Section 13 and 15(d)


Cover - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Mar. 25, 2022
Jun. 30, 2021
Document Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2021    
Current Fiscal Year End Date --12-31    
Document Transition Report false    
Entity File Number 001-40209    
Entity Registrant Name Heliogen, Inc.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 85-4204953    
Entity Address, Address Line One 130 West Union Street    
Entity Address, City or Town Pasadena    
Entity Address, State or Province CA    
Entity Address, Postal Zip Code 91103    
City Area Code 626    
Local Phone Number 720-4530    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company true    
Entity Ex Transition Period true    
ICFR Auditor Attestation Flag false    
Entity Shell Company false    
Entity Public Float     $ 242.5
Entity Common Stock, Shares Outstanding   185,305,679  
Entity Central Index Key 0001840292    
Document Fiscal Year Focus 2021    
Document Fiscal Period Focus FY    
Amendment Flag false    
Documents Incorporated by Reference None.    
Common stock      
Document Information [Line Items]      
Title of 12(b) Security Common stock, $0.0001 par value per share    
Trading Symbol HLGN    
Security Exchange Name NYSE    
Document Information [Line Items]      
Title of 12(b) Security Warrants, each whole warrant exercisable for shares of Common stock at an exercise price of $11.50 per share    
Trading Symbol HLGN.W    
Security Exchange Name NYSE