v3.26.1
Document and Entity Information - shares
 6 Months Ended
Apr. 30, 2026
Jun. 04, 2026
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Apr. 30, 2026  
Document Transition Report false  
Entity File Number 1-14204  
Entity Registrant Name FUELCELL ENERGY, INC.  
Entity Incorporation, State or Country Code DE  
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 Address, Postal Zip Code 06810  
Country Region 203  
City Area Code 825  
Local Phone Number 6000  
Title of 12(b) Security Common stock, par value $0.0001 per share  
Trading Symbol FCEL  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   67,608,173
Entity Central Index Key 0000886128  
Amendment Flag false  
Current Fiscal Year End Date --10-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2