Document and Entity Information - shares	9 Months Ended
	Jul. 31, 2019	Sep. 06, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	FUELCELL ENERGY INC
Entity Central Index Key	0000886128
Document Type	10-Q
Document Period End Date	Jul. 31, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	FCEL
Current Fiscal Year End Date	--10-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity File Number	1-14204
Entity Tax Identification Number	060853042
Entity Common Stock, Shares Outstanding		125,914,240
Entity Address, State or Province	Connecticut
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Address, Address Line One	3 Great Pasture Road
Entity Address, City or Town	Danbury
Entity Address, Postal Zip Code	06810
City Area Code	(203)
Local Phone Number	825-6000