Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total Stockholder's Equity [Member]	Common Stock	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Deferred Compensation [Member]	Noncontrolling Interests [Member]	Series B Preferred Stock	Total
Beginning Balance at Oct. 31, 2020	$ 194,548	$ 29	$ 1,359,454	$ (1,164,196)	$ (739)	$ (432)	$ 432			$ 194,548
Beginning Balance at (in shares) at Oct. 31, 2020		294,706,758
Sale of common stock, net of fees	525,895	$ 8	525,887							525,895
Sale of common stock, net of fees (in shares)		69,074,573
Orion warrant exercises and other warrant exercises	22,093		22,093							22,093
Orion warrant exercises and other warrant exercises (in shares)		2,714,026
Common stock issued, non-employee compensation	275		275							$ 275
Common stock issued, non-employee compensation (in shares)		31,889								31,889
Share based compensation	4,293		4,293							$ 4,293
Stock issued under benefit plans, net of taxes paid upon vesting of restricted stock awards	(331)		(331)							(331)
Stock issued under benefit plans, net of taxes paid upon vesting of restricted stock awards (in shares)		108,511
Preferred dividends - Series B	(3,200)		(3,200)						$ (3,200)	(3,200)
Effect of foreign currency translation	80				80					80
Adjustment for deferred compensation						(154)	154
Adjustment for deferred compensation (in shares)		(17,019)
Release of a share reserve		(45)
Net loss attributable to noncontrolling interests										(30)
Net loss attributable to FuelCell Energy, Inc.	(101,055)			(101,055)						(101,055)
Net loss										(101,025)
Ending Balance at Oct. 31, 2021	642,438	$ 37	1,908,471	(1,265,251)	(819)	(586)	586			642,438
Ending Balance at (in shares) at Oct. 31, 2021		366,618,693
Sale of common stock, net of fees	183,552	$ 4	183,548							183,552
Sale of common stock, net of fees (in shares)		38,396,904
Common stock issued, non-employee compensation	305		305							$ 305
Common stock issued, non-employee compensation (in shares)		76,848								76,848
Share based compensation	6,792		6,792							$ 6,792
Stock issued under benefit plans, net of taxes paid upon vesting of restricted stock awards	(1,840)		(1,840)							(1,840)
Stock issued under benefit plans, net of taxes paid upon vesting of restricted stock awards (in shares)		539,950
Preferred dividends - Series B	(3,200)		(3,200)						(3,200)	(3,200)
Effect of foreign currency translation	933				933					933
Adjustment for deferred compensation						(269)	269
Adjustment for deferred compensation (in shares)		(69,407)
Reclassification of noncontrolling interest								$ 12,419		12,419
Return of capital to noncontrolling interest								(496)		(496)
Distribution to noncontrolling interest								(308)		(308)
Net loss attributable to noncontrolling interests	4,510			4,510				(4,510)		4,510
Net loss attributable to FuelCell Energy, Inc.										(142,722)
Net loss	(147,232)			(147,232)						(147,232)
Ending Balance at Oct. 31, 2022	684,392	$ 41	2,094,076	(1,407,973)	(1,752)	(855)	855	7,105		$ 691,497
Ending Balance at (in shares) at Oct. 31, 2022		405,562,988								405,562,988
Sale of common stock, net of fees	97,439	$ 4	97,435							$ 97,439
Sale of common stock, net of fees (in shares)		44,320,825
Common stock issued, non-employee compensation	225		225							$ 225
Common stock issued, non-employee compensation (in shares)		103,631								103,631
Share based compensation	11,954		11,954							$ 11,954
Stock issued under benefit plans, net of taxes paid upon vesting of restricted stock awards	(829)		(829)							(829)
Stock issued under benefit plans, net of taxes paid upon vesting of restricted stock awards (in shares)		743,049
Preferred dividends - Series B	(3,200)		(3,200)						$ (3,200)	(3,200)
Effect of foreign currency translation	(80)				(80)					(80)
Adjustment for deferred compensation						(223)	223
Adjustment for deferred compensation (in shares)		(103,631)
Contributions received for the sale of noncontrolling interest								9,052		9,052
Reclassification of noncontrolling interest								3,030		3,030
Distribution to noncontrolling interest								(744)		(744)
Net loss attributable to noncontrolling interests	488			488				(488)		488
Net loss attributable to FuelCell Energy, Inc.										(107,568)
Net loss	(108,056)			(108,056)						(108,056)
Ending Balance at Oct. 31, 2023	$ 682,493	$ 45	$ 2,199,661	$ (1,515,541)	$ (1,672)	$ (1,078)	$ 1,078	$ 17,955		$ 700,448
Ending Balance at (in shares) at Oct. 31, 2023		450,626,862								450,626,862