Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Series D Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Series D Preferred Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Deferred Compensation [Member]
Balance at at Oct. 31, 2018	$ 82,194		$ 1	$ 1,073,463		$ (990,867)	$ (403)	$ (363)	$ 363
Balance at (in shares) at Oct. 31, 2018			7,972,686
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation	987			987
Fee adjustment for common stock issuance	90			90
Taxes paid upon vesting of restricted stock awards, net of stock issued under benefit plans	27			27
Taxes paid upon vesting of restricted stock awards, net of stock issued under benefit plans, (in shares)			1,946
Series C convertible preferred stock conversions	1,974			1,974
Series C convertible preferred stock conversions, (in shares)			127,829
Series C convertible preferred stock adjustment for beneficial conversion feature	6,586			6,586
Series C convertible stock redemption value adjustments	(8,550)			(8,550)
Series D convertible preferred stock conversions	4,334			4,334
Series D convertible preferred stock conversions, (in shares)			932,144
Convertible preferred stock redemption accretion		$ (3,793)			$ (3,793)
Preferred dividends — Series B	(800)			(800)
Impact of the adoption of Topic 606	(6,654)					(6,654)
Effect of foreign currency translation	7						7
Net loss attributable to FuelCell Energy, Inc.	(17,548)					(17,548)
Balance at at Jan. 31, 2019	58,854		$ 1	1,074,318		(1,015,069)	(396)	(363)	363
Balance at (in shares) at Jan. 31, 2019			9,034,605
Balance at at Oct. 31, 2019	$ 75,737		$ 19	1,151,454		(1,075,089)	(647)	(466)	466
Balance at (in shares) at Oct. 31, 2019	193,608,684		193,608,684
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation	$ 488			488
Orion warrant exercises	25,994		$ 1	25,993
Orion warrant exercises, shares			9,396,320
Sale of common stock, net of fees	3,502		$ 1	3,501
Sale of common stock, net of fees (in shares)			7,938,228
Taxes paid upon vesting of restricted stock awards, net of stock issued under benefit plans	(6)			(6)
Taxes paid upon vesting of restricted stock awards, net of stock issued under benefit plans, (in shares)			2,585
Preferred dividends — Series B	(931)			(931)
Adjustment for deferred compensation									(29)
Adjustment for deferred compensation, (in shares)			20,012
Adjustment for deferred compensation								29
Effect of foreign currency translation	(49)						(49)
Net loss attributable to FuelCell Energy, Inc.	(40,151)					(40,151)
Balance at at Jan. 31, 2020	$ 64,584		$ 21	$ 1,180,499		$ (1,115,240)	$ (696)	$ (437)	$ 437
Balance at (in shares) at Jan. 31, 2020	210,965,829		210,965,829