Loss Per Share - Schedule of Calculation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Oct. 31, 2023	Oct. 31, 2022	Oct. 31, 2021
Numerator
Net loss attributable to FuelCell Energy, Inc.	$ (107,568)	$ (142,722)	$ (101,055)
Series B preferred stock dividends	(3,200)	(3,200)	(3,200)
Net loss attributable to common stockholders	$ (110,768)	$ (145,922)	$ (104,255)
Denominator
Weighted average common shares outstanding - basic	419,747,796	383,139,140	334,742,346
Weighted average common shares outstanding - diluted	419,747,796	383,139,140	334,742,346
Net loss to common stockholders per share - basic	$ (0.26)	$ (0.38)	$ (0.31)
Net loss to common stockholders per share - diluted	$ (0.26)	$ (0.38)	$ (0.31)
Series B Preferred Stock
Numerator
Series B preferred stock dividends	$ (3,200)	$ (3,200)	$ (3,200)