Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jul. 31, 2022	Jul. 31, 2021	Jul. 31, 2022	Jul. 31, 2021
Revenues:
Revenues	$ 43,104	$ 26,820	$ 91,283	$ 55,650
Costs of revenues:
Costs of revenues	47,284	25,720	105,668	62,924
Gross (loss) profit	(4,180)	1,100	(14,385)	(7,274)
Operating expenses:
Administrative and selling expenses	14,158	8,662	64,357	27,264
Research and development expenses	9,659	3,023	22,316	7,810
Total costs and expenses	23,817	11,685	86,673	35,074
Loss from operations	(27,997)	(10,585)	(101,058)	(42,348)
Interest expense	(1,622)	(1,554)	(4,757)	(5,662)
Loss on extinguishment of debt				(11,156)
Loss on extinguishment of Series 1 preferred share obligation				(934)
Change in fair value of common stock warrant liability				(15,974)
Other income (expense), net	1,136	149	1,086	(797)
Loss before provision for income taxes	(28,483)	(11,990)	(104,729)	(76,871)
Provision for income taxes	(494)	(7)	(494)	(3)
Net loss	(28,977)	(11,997)	(105,223)	(76,874)
Net income (loss) attributable to noncontrolling interest	437		(4,968)
Net loss attributable to FuelCell Energy, Inc.	(29,414)	(11,997)	(100,255)	(76,874)
Series B preferred stock dividends	(800)	(800)
Net loss attributable to common stockholders	$ (30,214)	$ (12,797)	$ (102,655)	$ (79,274)
Loss per share basic and diluted:
Net loss per share attributable to common stockholders, basic	$ (0.08)	$ (0.04)	$ (0.27)	$ (0.24)
Net loss per share attributable to common stockholders, diluted	$ (0.08)	$ (0.04)	$ (0.27)	$ (0.24)
Basic weighted average shares outstanding	387,465,758	337,291,562	375,638,293	323,983,465
Diluted weighted average shares outstanding	387,465,758	337,291,562	375,638,293	323,983,465
Net loss	$ (28,977)	$ (11,997)	$ (105,223)	$ (76,874)
Other comprehensive loss:
Foreign currency translation adjustments	(86)	(6)	(326)	(8)
Total comprehensive loss	(29,063)	(12,003)	(105,549)	(76,882)
Comprehensive income (loss) attributable to noncontrolling interest	437		(4,968)
Comprehensive loss attributable to FuelCell Energy, Inc.	(29,500)	(12,003)	(100,581)	(76,882)
Series B Preferred Stock
Operating expenses:
Series B preferred stock dividends	(800)	(800)	(2,400)	(2,400)
Product
Revenues:
Revenues	18,000		36,000
Costs of revenues:
Costs of revenues	17,919	1,903	39,159	6,190
Service
Revenues:
Revenues	9,049	14,344	13,855	19,917
Costs of revenues:
Costs of revenues	7,718	13,026	13,123	20,992
Generation
Revenues:
Revenues	10,877	6,230	27,423	17,306
Costs of revenues:
Costs of revenues	18,136	6,728	42,978	23,265
Advanced Technologies
Revenues:
Revenues	5,178	6,246	14,005	18,427
Costs of revenues:
Costs of revenues	$ 3,511	$ 4,063	$ 10,408	$ 12,477