Consolidated Statements of Changes in (Deficit) Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Deferred Compensation [Member]	Noncontrolling Interest In Subsidiaries [Member]
Balance at (in shares) at Oct. 31, 2013		16,359,200
Balance at at Oct. 31, 2013	$ (13,192)	$ 2	$ 758,674	$ (771,189)	$ 101	$ (53)	$ 53	$ (780)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Sale of common stock (in shares)		4,973,604
Sale of common stock	105,966	$ 0	105,966
Common stock issued for convertible note conversions including interest, shares		2,063,896
Common stock issued for convertible note conversions including interest, value	33,306	$ 0	33,306
Common stock issued to settle make-whole obligation, shares		459,523
Common stock issued to settle make-whole obligation, value	12,883		12,883
Share based compensation	2,908		2,908
Stock issued under benefit plans (in shares)		76,136
Stock issued under benefit plans	(1,079)		(1,079)
Preferred stock dividends	(3,200)		(3,200)
Adjustment for deferred compensation (in shares)		(2,359)
Adjustment for deferred compensation						(42)
Adjustment for deferred compensation	0						42
Noncontrolling interest in subsidiaries	(758)							(758)
Foreign currency translation adjustments	(260)				(260)
Net loss attributable to FuelCell Energy, Inc.	(38,125)			(38,125)
Balance at (in shares) at Oct. 31, 2014		23,930,000
Balance at at Oct. 31, 2014	98,449	$ 2	909,458	(809,314)	(159)	(95)	95	(1,538)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Sale of common stock (in shares)		1,845,166
Sale of common stock	26,921	$ 1	26,920
Share based compensation	3,157		3,157
Stock issued under benefit plans (in shares)		191,593
Stock issued under benefit plans	(539)		(539)
Purchase of non-controlling shares of subsidiary	0		1,308					1,308
Preferred stock dividends	(3,200)		(3,200)
Adjustment for deferred compensation (in shares)		(2,049)
Adjustment for deferred compensation						17
Adjustment for deferred compensation	0						(17)
Noncontrolling interest in subsidiaries	(325)							(325)
Foreign currency translation adjustments	(350)				(350)
Net loss attributable to FuelCell Energy, Inc.	$ (29,359)			(29,359)
Balance at (in shares) at Oct. 31, 2015	25,964,710	25,964,710
Balance at at Oct. 31, 2015	$ 94,754	$ 3	934,488	(838,673)	(509)	(78)	78	(555)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Sale of common stock (in shares)		6,023,372
Sale of common stock	36,056	$ 1	36,055
Common stock issued, non-employee compensation, in shares		24,379
Common stock issued, non-employee compensation	157		157
Exercise of prepaid warrants, in shares		1,100,000
Sale of common stock and prepaid warrants, public offering, in shares		1,474,000
Sale of common stock and prepaid warrants, public offering	34,736		34,736
Share based compensation	3,425		3,425
Stock issued under benefit plans (in shares)		587,963
Stock issued under benefit plans	(286)		(286)
Purchase of non-controlling shares of subsidiary	(3)		(809)					806
Preferred stock dividends	(3,200)		(3,200)
Adjustment for deferred compensation						(101)
Adjustment for deferred compensation							101
Noncontrolling interest in subsidiaries	(251)							(251)
Foreign currency translation adjustments	(35)				(35)
Net loss attributable to FuelCell Energy, Inc.	$ (50,957)			(50,957)
Balance at (in shares) at Oct. 31, 2016	35,174,424	35,174,424
Balance at at Oct. 31, 2016	$ 114,396	$ 4	$ 1,004,566	$ (889,630)	$ (544)	$ (179)	$ 179	$ 0