Loss Per Share - Calculation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Jan. 31, 2022	Jan. 31, 2021
Numerator
Net loss attributable to FuelCell Energy, Inc.		$ (40,624)	$ (45,960)
Warrant exchange			15,974
Preferred dividends - Series B		(800)	(800)
Net loss attributable to common stockholders		$ (41,424)	$ (46,760)
Denominator
Weighted average common shares outstanding - basic		366,734,739	312,109,888
Effect of dilutive securities	[1]	0	0
Weighted average common shares outstanding - diluted		366,734,739	312,109,888
Net loss to common stockholders per share - basic		$ (0.11)	$ (0.15)
Net loss to common stockholders per share - diluted	[1]	$ (0.11)	$ (0.15)
Series B Preferred Stock
Numerator
Preferred dividends - Series B		$ (800)	$ (800)

[1] Due to the net loss to common stockholders in each of the periods presented above, diluted loss per share was computed without consideration to potentially dilutive instruments as their inclusion would have been anti-dilutive.