Document and Entity Information - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Oct. 31, 2017	Jan. 02, 2018	Apr. 28, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	FUELCELL ENERGY INC
Entity Central Index Key	0000886128
Document Type	10-K
Document Period End Date	Oct. 31, 2017
Amendment Flag	false
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	FCEL
Current Fiscal Year End Date	--10-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		75,678,919
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 54,054,838
Share Price			$ 1.15