Cover - shares	9 Months Ended
	Sep. 30, 2023	Nov. 09, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
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 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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		5,908,645
Entity Central Index Key	0001840292
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
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
Warrants
Document Information [Line Items]
Title of 12(b) Security	Warrants, each 35 warrants exercisable for one share of common stock at an exercise price of $402.50 per share
Trading Symbol	HLGN.W
Security Exchange Name	NYSE
Preferred Share Purchase Right
Document Information [Line Items]
Title of 12(b) Security	Preferred Share Purchase Rights
No Trading Symbol Flag	true
Security Exchange Name	NYSE