Document and Entity Information - USD ($)	12 Months Ended
	Oct. 31, 2023	Dec. 14, 2023	Apr. 28, 2023
Cover [Abstract]
Entity Registrant Name	FUELCELL ENERGY, INC.
Entity Central Index Key	0000886128
Document Type	10-K
Document Period End Date	Oct. 31, 2023
Current Fiscal Year End Date	--10-31
Document Transition Report	false
Amendment Flag	false
Entity File Number	1-14204
Entity Tax Identification Number	06-0853042
Entity Address, Address Line One	3 Great Pasture Road
Entity Address, City or Town	Danbury
Entity Address, State or Province	CT
Entity Incorporation, State or Country Code	DE
Entity Address, Postal Zip Code	06810
City Area Code	203
Local Phone Number	825-6000
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	FCEL
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Document Annual Report	true
Entity Well-known Seasoned Issuer	Yes
ICFR Auditor Attestation Flag	true
Entity Voluntary Filers	No
Entity Public Float			$ 763,367,486
Entity Common Stock, Shares Outstanding		451,804,288
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Auditor Name	KPMG LLP
Auditor Firm ID	185
Auditor Location	Hartford, Connecticut