Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2024	Apr. 30, 2023
Revenues:
Total revenues	$ 22,420	$ 38,349	$ 39,111	$ 75,422
Costs of revenues:
Total costs of revenues	29,494	44,442	57,910	76,278
Gross loss	(7,074)	(6,093)	(18,799)	(856)
Operating expenses:
Administrative and selling expenses	17,660	15,068	34,060	30,077
Research and development expenses	16,627	14,697	30,980	27,380
Total costs and expenses	34,287	29,765	65,040	57,457
Loss from operations	(41,361)	(35,858)	(83,839)	(58,313)
Interest expense	(2,275)	(1,502)	(4,613)	(3,014)
Interest income	3,390	3,688	7,457	7,098
Other income (expense), net	2,590	(236)	(1,060)	(187)
Loss before provision for income taxes	(37,656)	(33,908)	(82,055)	(54,416)
Provision for income taxes		(3)		(581)
Net loss	(37,656)	(33,911)	(82,055)	(54,997)
Net (loss) income attributable to noncontrolling interests	(5,516)	392	(30,122)	(2,072)
Net loss attributable to FuelCell Energy, Inc.	(32,140)	(34,303)	(51,933)	(52,925)
Series B preferred stock dividends	(800)	(800)	(1,600)	(1,600)
Net loss attributable to common stockholders	$ (32,940)	$ (35,103)	$ (53,533)	$ (54,525)
Loss per share basic and diluted:
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.07)	$ (0.09)	$ (0.12)	$ (0.13)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.07)	$ (0.09)	$ (0.12)	$ (0.13)
Basic weighted average shares outstanding (in shares)	452,984,445	406,316,070	452,303,339	406,055,027
Diluted weighted average shares outstanding (in shares)	452,984,445	406,316,070	452,303,339	406,055,027
Net loss	$ (37,656)	$ (33,911)	$ (82,055)	$ (54,997)
Other comprehensive loss:
Foreign currency translation adjustments	(78)	(151)	(45)	296
Total comprehensive loss	(37,734)	(34,062)	(82,100)	(54,701)
Comprehensive (loss) income attributable to noncontrolling interests	(5,516)	392	(30,122)	(2,072)
Comprehensive loss attributable to FuelCell Energy, Inc.	(32,218)	(34,454)	(51,978)	(52,629)
Series B Preferred Stock
Operating expenses:
Series B preferred stock dividends	(800)	(800)	(1,600)	(1,600)
Product
Revenues:
Total revenues				9,095
Costs of revenues:
Total costs of revenues	2,938	3,486	5,329	4,515
Service
Revenues:
Total revenues	1,369	26,190	2,986	40,072
Costs of revenues:
Total costs of revenues	1,267	20,113	3,155	31,058
Generation
Revenues:
Total revenues	14,118	8,440	24,611	17,997
Costs of revenues:
Total costs of revenues	21,424	17,081	42,318	33,683
Advanced Technologies
Revenues:
Total revenues	6,933	3,719	11,514	8,258
Costs of revenues:
Total costs of revenues	$ 3,865	$ 3,762	$ 7,108	$ 7,022