Subsequent Events	12 Months Ended
Oct. 31, 2012
Subsequent Events [Abstract]
Subsequent Events	Note 20. Subsequent Events Versa Power Systems, Inc. acquisition In December 2012, the Company acquired the remaining 61% ownership position of Versa Power Systems, Inc. (Versa), a leading global developer of solid oxide fuel cell technology (SOFC). The transaction resulted in the Company exchanging approximately 3.5 million shares of its common stock for the remaining 61% of outstanding Versa shares held by the four Versa shareholders. The purchase price offered by FuelCell Energy during the fourth quarter of fiscal 2012 that the other shareholders were willing to accept was an indicator of impairment and as a result an impairment charge of the Company's prior investment classified as Investment in and loans to affiliate on the Consolidated Balance Sheets was recorded in the fourth quarter of 2012. There were no previous indicators identified to determine impairment. Versa will be fully consolidated into the Company's financial statements as of the acquisition date and step-acquisition accounting will be applied. Versa receives revenue under a number of research contracts including the U.S. Department of Energy Solid State Energy Conversion Alliance (SECA) coal-based systems program and a research contract with The Boeing Company. Revenue and associated costs are expected to be recognized under Research and development contracts in the consolidated financial statements of FuelCell Energy, Inc. Bridgeport Project In December 2012, the Company announced the sale of a 14.9 MW fuel cell park in Bridgeport, Connecticut with the power plants sold to Dominion, one of the largest utilities in the USA with operations in 15 States. Five 2.8 MW DFC3000® power plants will supply 14.0 megawatts of ultra-clean electricity and heat from the fuel cells will be converted into an additional 0.9 MW of virtually emission free electricity through use of an organic rankine cycle configuration. Connecticut Light & Power will purchase the electricity from Dominion under a 15 year energy purchase agreement. Fuel cell parks assist utilities in adding environmentally friendly and economical baseload power generation throughout their service area, reducing congestion of their existing transmission and distribution grid. This project will increase product and service backlog in the first quarter of 2013 by approximately $125 million, including approximately $56 million for product backlog and $69 million for service backlog. Bridgeport FuelCell Park, LLC (“BFCP”), one of our wholly-owned subsidiaries, has an outstanding loan with the Connecticut Clean Energy Fund, secured by assets of BFCP. Interest accrues monthly at an annual rate of 8.75 percent and repayment of principal and accrued interest is not required until the occurrence of certain events. The outstanding balance on this loan, including accrued interest, is $0.8 million as of October 31, 2012. The Connecticut Clean Energy and Finance Investment Authority (CEFIA) is the successor agency to the Connecticut Clean Energy Fund. In conjunction with the closing of the sale of the Bridgeport project and sale of the project assets from BFCP to Dominion in December 2012, the Board of CEFIA approved a resolution to provide a new loan agreement of approximately $5.8 million to FuelCell Energy specific to the Company's support of this project. A portion of the proceeds of this new loan will be used to repay the BFCP loan and the balance will be drawn down during 2013 as working capital support. As of January 14, 2013, the new loan agreement and terms are now being finalized with CEFIA. We expect the new loan agreement to carry an interest rate of 5.0 percent and principal will be repayable commencing on the eighth anniversary of the project's provisional acceptance date in forty eight equal monthly installments.

Note 20. Subsequent Events

Versa Power Systems, Inc. acquisition

In December 2012, the Company acquired the remaining 61% ownership position of Versa Power Systems, Inc. (Versa), a leading global developer of solid oxide fuel cell technology (SOFC).

The transaction resulted in the Company exchanging approximately 3.5 million shares of its common stock for the remaining 61% of outstanding Versa shares held by the four Versa shareholders. The purchase price offered by FuelCell Energy during the fourth quarter of fiscal 2012 that the other shareholders were willing to accept was an indicator of impairment and as a result an impairment charge of the Company's prior investment classified as Investment in and loans to affiliate on the Consolidated Balance Sheets was recorded in the fourth quarter of 2012. There were no previous indicators identified to determine impairment.

Versa will be fully consolidated into the Company's financial statements as of the acquisition date and step-acquisition accounting will be applied. Versa receives revenue under a number of research contracts including the U.S. Department of Energy Solid State Energy Conversion Alliance (SECA) coal-based systems program and a research contract with The Boeing Company. Revenue and associated costs are expected to be recognized under Research and development contracts in the consolidated financial statements of FuelCell Energy, Inc.

Bridgeport Project

In December 2012, the Company announced the sale of a 14.9 MW fuel cell park in Bridgeport, Connecticut with the power plants sold to Dominion, one of the largest utilities in the USA with operations in 15 States. Five 2.8 MW DFC3000® power plants will supply 14.0 megawatts of ultra-clean electricity and heat from the fuel cells will be converted into an additional 0.9 MW of virtually emission free electricity through use of an organic rankine cycle configuration. Connecticut Light & Power will purchase the electricity from Dominion under a 15 year energy purchase agreement. Fuel cell parks assist utilities in adding environmentally friendly and economical baseload power generation throughout their service area, reducing congestion of their existing transmission and distribution grid. This project will increase product and service backlog in the first quarter of 2013 by approximately $125 million, including approximately $56 million for product backlog and $69 million for service backlog.

Bridgeport FuelCell Park, LLC (“BFCP”), one of our wholly-owned subsidiaries, has an outstanding loan with the Connecticut Clean Energy Fund, secured by assets of BFCP. Interest accrues monthly at an annual rate of 8.75 percent and repayment of principal and accrued interest is not required until the occurrence of certain events. The outstanding balance on this loan, including accrued interest, is $0.8 million as of October 31, 2012. The Connecticut Clean Energy and Finance Investment Authority (CEFIA) is the successor agency to the Connecticut Clean Energy Fund. In conjunction with the closing of the sale of the Bridgeport project and sale of the project assets from BFCP to Dominion in December 2012, the Board of CEFIA approved a resolution to provide a new loan agreement of approximately $5.8 million to FuelCell Energy specific to the Company's support of this project. A portion of the proceeds of this new loan will be used to repay the BFCP loan and the balance will be drawn down during 2013 as working capital support. As of January 14, 2013, the new loan agreement and terms are now being finalized with CEFIA. We expect the new loan agreement to carry an interest rate of 5.0 percent and principal will be repayable commencing on the eighth anniversary of the project's provisional acceptance date in forty eight equal monthly installments.