| Cover | Apr. 08, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K/A |
| Amendment Flag | true |
| Amendment Description | This Form 8-K/A (Amendment No. 1) is being filed solely to include the reference to Exhibit 104, Cover Page Interactive Data File (embedded within the Inline XBRL document) which was inadvertently omitted from the Form 8-K filed on April 8, 2021. No change other than the addition of the exhibit reference is being made by this Form 8-K/A (Amendment No. 1). |
| Document Period End Date | Apr. 8, 2021 |
| Entity Registrant Name | FUELCELL ENERGY, INC. |
| Entity Central Index Key | 0000886128 |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, $0.0001 par value per share |
| Trading Symbol | FCEL |
| Security Exchange Name | NASDAQ |
| Entity File Number | 1-14204 |
| 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 |
| City Area Code | 203 |
| Local Phone Number | 825-6000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
