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Stockholders' Equity and Warrant Liabilities - Additional Information (Details) - USD ($)									1 Months Ended	3 Months Ended	5 Months Ended	12 Months Ended
	Oct. 06, 2020	Jun. 16, 2020	Jan. 09, 2020	Jan. 08, 2020	Oct. 04, 2019	Feb. 21, 2019	Jun. 13, 2018	May 03, 2017	Oct. 31, 2020	Jan. 31, 2020	Oct. 31, 2020	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2018	May 11, 2020	Apr. 30, 2020	Nov. 22, 2019	May 08, 2019	Jul. 12, 2016
Stockholders' Equity Note
Common stock, par value									$ 0.0001		$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares issued									294,706,758		294,706,758	294,706,758	193,608,684
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.242								$ 0.242		$ 0.242	$ 0.242
Expected volatility	113.84%			103.70%								114.15%	96.00%
Risk-free interest rate	0.55%									1.81%		0.64%	1.63%	2.80%
Common stock price per share	$ 1.92			$ 2.29					$ 2.00		$ 2.00	$ 2.00	$ 0.24			$ 2.02
Expected life (years)													8 years	7 years
Class of warrants or rights issued value													$ 3,900,000
Common stock, shares authorized									337,500,000		337,500,000	337,500,000	225,000,000		112,500,000			225,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.242								$ 0.242		$ 0.242	$ 0.242
Change in fair value of common stock warrant liability												$ 37,086,000	$ 0	$ 0
Expected volatility	113.84%			103.70%								114.15%	96.00%
Risk-free interest rate	0.55%									1.81%		0.64%	1.63%	2.80%
Share Price	$ 1.92			$ 2.29					$ 2.00		$ 2.00	$ 2.00	$ 0.24			$ 2.02
Class of warrants or rights charge										$ 23,700,000		$ 200,000
Reclassification of estimated fair value of warrant liability to additional paid in capital	$ 9,800,000			$ 26,000,000.0
Class of warrants to purchase	5,300,000								2,700,000		2,700,000	2,700,000
Payments for repurchase of warrants	$ 1,300,000
Class of warrants or gain	2.4
Fair value of outstanding warrants									$ 5,200,000		$ 5,200,000	$ 5,200,000
Exchange Agreement [Member]
Stockholders' Equity Note
Common stock issued to warrant holders						500,000
Series C Warrants [Member]
Stockholders' Equity Note
Class of warrant or right, outstanding									964,114		964,114	964,114	964,114	964,114
Series A Warrants [Member]
Stockholders' Equity Note
Class of Warrant or Right, Exercise Price of Warrants or Rights																			$ 69.96
Class of warrant or right, outstanding														640,000					640,000
Class of Warrant or Right, Exercise Price of Warrants or Rights																			$ 69.96
Series A Warrants [Member] \| Exchange Agreement [Member]
Stockholders' Equity Note
Change in fair value of common stock warrant liability												$ 300,000
Fair value of the shares at the date of the Exchange Agreement												$ 3,500,000
Orion Energy Partners Investment Agent, LLC Credit Facility [Member] \| Initial Funding Warrants [Member]
Stockholders' Equity Note
Class of warrants or rights issued													6,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights													$ 0.310
Class of Warrant or Right, Exercise Price of Warrants or Rights													$ 0.310
Orion Energy Partners Investment Agent, LLC Credit Facility [Member] \| Second Funding Warrants [Member]
Stockholders' Equity Note
Class of warrants or rights issued																	14,000,000
Orion Energy Partners Investment Agent, LLC Credit Facility [Member] \| Second Funding Warrants [Member] \| Exercise Price 0.242 [Member]
Stockholders' Equity Note
Class of warrants or rights issued																	8,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights																	$ 0.242
Class of Warrant or Right, Exercise Price of Warrants or Rights																	$ 0.242
Orion Energy Partners Investment Agent, LLC Credit Facility [Member] \| Second Funding Warrants [Member] \| Exercise Price 0.620 [Member]
Stockholders' Equity Note
Class of warrants or rights issued																	6,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights																	$ 0.620
Class of Warrant or Right, Exercise Price of Warrants or Rights																	$ 0.620
Orion Energy Partners Investment Agent, LLC Credit Facility [Member]
Stockholders' Equity Note
Number of shares reserved for future issuance and sale			2,603,680
Stock issued during period, shares, new issues			9,396,320
Stock issued during period, shares, new issues			9,396,320
Class of warrant or right, outstanding									2,700,000		2,700,000	2,700,000	6,000,000
Number of shares reserved for future issuance and sale			2,603,680
Orion Energy Partners Investment Agent, LLC Credit Facility [Member] \| Initial Funding Warrants [Member]
Stockholders' Equity Note
Number Of Securities Called By Warrants			6,000,000
Orion Energy Partners Investment Agent, LLC Credit Facility [Member] \| Initial Funding Warrants [Member] \| Exercise Price 0.310 [Member]
Stockholders' Equity Note
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 0.31
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 0.31
Class of warrants or rights exercised			12,000,000
Orion Energy Partners Investment Agent, LLC Credit Facility [Member] \| Second Funding [Member]
Stockholders' Equity Note
Number Of Securities Called By Warrants			6,000,000
Orion Energy Partners Investment Agent, LLC Credit Facility [Member] \| Second Funding [Member] \| Exercise Price 0.620 [Member]
Stockholders' Equity Note
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 0.62
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 0.62
Class of warrants or rights exercised			12,000,000
At Market Issuance Sales Agreement \| B. Riley FBR, Inc [Member]
Stockholders' Equity Note
Number of shares reserved for future issuance and sale					27,900,000
Reserve for issuance of common stock upon exercise of warrants shares													20,000,000.0
Percentage of sales commission					3.00%
Percentage of sales commission					3.00%
Number of shares reserved for future issuance and sale					27,900,000
At Market Issuance Sales Agreement \| B. Riley FBR, Inc [Member] \| Maximum [Member]
Stockholders' Equity Note
Aggregate offering price					$ 38,000,000.0
Number of shares reserved for future issuance and sale													7,900,000
Common stock, shares issued													18,000,000.0
Stock issued during period, shares, new issues					$ 38,000,000.0
Number of shares reserved for future issuance and sale													7,900,000
At Market Issuance Sales Agreement \| B. Riley FBR, Inc and Oppenheimer & Co. Inc. [Member]
Stockholders' Equity Note
Percentage of sales commission							3.00%
Percentage of sales commission							3.00%
At Market Issuance Sales Agreement \| B. Riley FBR, Inc and Oppenheimer & Co. Inc. [Member] \| Maximum [Member]
Stockholders' Equity Note
Aggregate offering price							$ 50,000,000.0
Stock issued during period, shares, new issues							$ 50,000,000.0
Underwriting Agreement
Stockholders' Equity Note
Stock issued during period, shares, new issues									50,000,000.0
Stock issued during period, shares, new issues									50,000,000.0
Gross proceeds from offering									$ 105,100,000
Net proceeds from issuance of public offerings									$ 98,300,000
Underwritten Public Offering [Member] \| Series C Warrants [Member]
Stockholders' Equity Note
Class of warrants or rights issued								1,000,000
Warrants issued, price per share								$ 19.20
Class of Warrant or Right, Exercise Price of Warrants or Rights								$ 19.20
Class of warrant or right term								5 years
Class of Warrant or Right, Exercise Price of Warrants or Rights								$ 19.20
Underwritten Public Offering [Member] \| Series D Warrants [Member]
Stockholders' Equity Note
Class of warrants or rights issued								1,000,000
Warrants issued, price per share								$ 15.36
Class of Warrant or Right, Exercise Price of Warrants or Rights								$ 15.36
Class of warrant or right term								1 year
Class of Warrant or Right, Exercise Price of Warrants or Rights								$ 15.36
Common Stock [Member]
Stockholders' Equity Note
Stock issued during period, shares, new issues												86,307,932	119,128,677	476,265
Stock issued during period, shares, new issues												86,307,932	119,128,677	476,265
Common Stock [Member] \| Series C Warrants [Member]
Stockholders' Equity Note
Stock issued during period, shares, new issues												0	0	962
Net proceeds from common stock and warrants														$ 20,000.00
Stock issued during period, shares, new issues												0	0	962
Common Stock [Member] \| Series D Warrants [Member]
Stockholders' Equity Note
Stock issued during period, shares, new issues														215,347
Net proceeds from common stock and warrants														$ 3,300,000
Stock issued during period, shares, new issues														215,347
Common Stock [Member] \| At Market Issuance Sales Agreement \| Jefferies LLC [Member]
Stockholders' Equity Note
Percentage of sales commission		3.00%
Stock issued during period, shares, new issues											28,300,000
Average sale price per share									$ 2.55		$ 2.55	$ 2.55
Stock issued during period on sales agreement											$ 72,300,000
Sales commissions paid to agent											2,200,000
Stock issued during period on sales agreement											72,300,000
Sale of common stock net of fees											$ 2,200,000
Percentage of sales commission		3.00%
Stock issued during period, shares, new issues											28,300,000
Average sale price per share									2.55		$ 2.55	$ 2.55
Stock issued during period on sales agreement											$ 72,300,000
Sales commissions paid to agent											2,200,000
Stock issued during period on sales agreement											$ 70,100,000
Common Stock [Member] \| At Market Issuance Sales Agreement \| Jefferies LLC [Member] \| Maximum [Member]
Stockholders' Equity Note
Aggregate offering price		$ 75,000,000
Stock issued during period, shares, new issues		$ 75,000,000
Common Stock [Member] \| At Market Issuance Sales Agreement \| B. Riley FBR, Inc [Member]
Stockholders' Equity Note
Stock issued during period, shares, new issues												7,900,000	10,100,000
Average sale price per share									0.46		$ 0.46	$ 0.46
Stock issued during period on sales agreement												$ 3,600,000	$ 3,000,000.0
Sales commissions paid to agent												100,000	100,000
Net proceeds on sales agreement												3,500,000	2,900,000
Stock issued during period on sales agreement												3,600,000	3,000,000.0
Sale of common stock net of fees												$ 100,000	$ 100,000
Stock issued during period, shares, new issues												7,900,000	10,100,000
Average sale price per share									$ 0.46		$ 0.46	$ 0.46
Stock issued during period on sales agreement												$ 3,600,000	$ 3,000,000.0
Sales commissions paid to agent												$ 100,000	$ 100,000
Common Stock [Member] \| At Market Issuance Sales Agreement \| B. Riley FBR, Inc and Oppenheimer & Co. Inc. [Member]
Stockholders' Equity Note
Stock issued during period, shares, new issues													109,100,000	500,000
Stock issued during period on sales agreement													$ 42,000,000.0	$ 8,000,000.0
Sales commissions paid to agent													1,300,000	200,000
Stock issued during period on sales agreement													42,000,000.0	8,000,000.0
Sale of common stock net of fees													$ 1,300,000	$ 200,000
Average sale price													$ 0.39	$ 16.72
Stock issued during period, shares, new issues													109,100,000	500,000
Stock issued during period on sales agreement													$ 42,000,000.0	$ 8,000,000.0
Sales commissions paid to agent													$ 1,300,000	$ 200,000
Warrant [Member] \| Second Funding Warrants [Member]
Stockholders' Equity Note
Percentage of warrants vesting													100.00%