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Stockholders' Equity and Warrant Liabilities - Additional Information (Details) - USD ($) |  |  |  |  | 12 Months Ended |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 04, 2019 | Feb. 21, 2019 | Jun. 13, 2018 | May 03, 2017 | Oct. 31, 2019 | Oct. 31, 2018 | Oct. 31, 2017 | Jan. 14, 2020 | Nov. 22, 2019 | May 08, 2019 | Apr. 30, 2019 | Apr. 04, 2019 | Dec. 14, 2017 | Apr. 30, 2017 | Oct. 31, 2016
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares authorized |  |  |  |  |  | 225,000,000 | 225,000,000 | 125,000,000 |  |  | 225,000,000 |  |  |  |  | 75,000,000
Common stock, par value |  |  |  |  |  | $ 0.0001 | $ 0.0001 |  |  |  |  |  |  |  |  |
Number of shares reserved for future issuance and sale |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,500,000 |
Common stock, shares issued |  |  |  |  |  | 193,608,684 | 7,972,686 |  |  |  |  |  |  |  |  |
Common stock price per share |  |  |  |  |  | $ 0.24 |  |  |  |  |  | $ 3.12 |  |  |  |
Class of Warrant or Right, Outstanding | [1] |  |  |  |  | 6,000,000 |  |  |  |  |  |  |  |  |  |
Expected volatility |  |  |  |  |  | 96.00% |  |  |  |  |  |  |  |  |  |
Risk-free interest rate |  |  |  |  |  | 1.63% | 2.80% | 2.20% |  |  |  |  |  |  |  |
Expected life (years) |  |  |  |  |  | 8 years | 7 years | 7 years |  |  |  |  |  |  |  |
Class of warrants or rights issued value |  |  |  |  |  | $ 3,900 |  |  |  |  |  |  |  |  |  |
Excess percentage of common shares outstanding |  |  |  |  |  |  |  |  |  |  |  |  | 19.90% | 19.90% |  |
Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares reserved for future issuance and sale |  |  |  |  |  |  |  |  | 10,290,934 |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |
Series A Warrants [Member] | Exchange Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of the warrant pre-modification |  |  |  |  |  | $ 300,000 |  |  |  |  |  |  |  |  |  |
Fair value of the shares at the date of the Exchange Agreement |  |  |  |  |  | $ 3,500,000 |  |  |  |  |  |  |  |  |  |
Series B Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Warrant or Right, Exercise Price of Warrants or Rights |  |  |  |  |  |  | $ 0.0012 |  |  |  |  |  |  |  |  |
Class of Warrant or Right, Outstanding |  |  |  |  |  |  | 410,500 |  |  |  |  |  |  |  |  | 318,834
Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares authorized |  |  |  |  |  |  |  |  |  |  |  |  | 335,000,000 |  |  |
Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares authorized |  |  |  |  |  |  |  |  |  |  |  |  | 225,000,000 |  |  |
Orion Credit Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Beneficial ownership, limitation on exercise of warrants |  |  |  |  |  | 4.99% |  |  |  |  |  |  |  |  |  |
Orion Credit Agreement [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 term |  |  |  |  |  | 8 years |  |  |  |  |  |  |  |  |  |
Orion Credit Agreement [Member] | Second Funding Warrants [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of warrants or rights issued |  |  |  |  |  |  |  |  |  | 14,000,000 |  |  |  |  |  |
Orion Credit Agreement [Member] | Second Funding Warrants [Member] | Exercise Price 0.242 [Member] | Subsequent Event [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 |  |  |  |  |  |
Orion Credit Agreement [Member] | Second Funding Warrants [Member] | Exercise Price 0.620 [Member] | Subsequent Event [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 |  |  |  |  |  |
At Market Issuance Sales Agreement [Member] | B. Riley FBR, Inc [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sales commission |  | 3.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |  |
At Market Issuance Sales Agreement [Member] | B. Riley FBR, Inc [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate offering price |  | $ 38,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares reserved for future issuance and sale |  |  |  |  |  | 7,900,000 |  |  |  |  |  |  |  |  |  |
Common stock, shares issued |  |  |  |  |  | 18,000,000 |  |  |  |  |  |  |  |  |  |
At Market Issuance Sales Agreement [Member] | B. Riley FBR, Inc and Oppenheimer & Co. Inc. [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of sales commission |  |  |  | 3.00% |  |  |  |  |  |  |  |  |  |  |  |
At Market Issuance Sales Agreement [Member] | B. Riley FBR, Inc and Oppenheimer & Co. Inc. [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate offering price |  |  |  | $ 50,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Underwritten Public Offering [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock issued during period, shares, new issues |  |  |  |  | 1,000,000 |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from common stock and warrants |  |  |  |  | $ 15,400,000 |  |  |  |  |  |  |  |  |  |  |
Common stock price per share |  |  |  |  | $ 15.36 |  |  |  |  |  |  |  |  |  |  |
Net proceeds from common stock and warrants |  |  |  |  | $ 13,900,000 |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  | $ 15.36 |  |  |  |  |  |  |  |  |  |  |
Class of Warrant or Right, Exercise Price of Warrants or Rights |  |  |  |  | $ 19.20 |  |  |  |  |  |  |  |  |  |  |
Class of warrant or right term |  |  |  |  | 5 years |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |  |  |
Common Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock issued during period, shares, new issues |  |  |  |  |  | 119,128,677 | 476,265 | 603,786 |  |  |  |  |  |  |  |
Common Stock [Member] | Series C Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock issued during period, shares, new issues |  |  |  |  |  | 0 | 962 |  |  |  |  |  |  |  |  |
Net proceeds from common stock and warrants |  |  |  |  |  |  | $ 20,000 |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  |
Common Stock [Member] | At Market Issuance Sales Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock issued during period, shares, new issues |  |  |  |  |  |  |  | 600,000 |  |  |  |  |  |  |  |
Stock issued during period on sales agreement |  |  |  |  |  |  |  | $ 12,600,000 |  |  |  |  |  |  |  |
Sale of common stock net of fees |  |  |  |  |  |  |  | $ 100,000 |  |  |  |  |  |  |  |
Average sale price |  |  |  |  |  |  |  | $ 21.00 |  |  |  |  |  |  |  |
Common Stock [Member] | At Market Issuance Sales Agreement [Member] | B. Riley FBR, Inc [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock issued during period, shares, new issues |  |  |  |  |  | 10,100,000 |  |  |  |  |  |  |  |  |  |
Stock issued during period on sales agreement |  |  |  |  |  | $ 3,000,000 |  |  |  |  |  |  |  |  |  |
Sale of common stock net of fees |  |  |  |  |  | $ 100,000 |  |  |  |  |  |  |  |  |  |
Common Stock [Member] | At Market Issuance Sales Agreement [Member] | 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 | $ 8,000,000 |  |  |  |  |  |  |  |  |
Sale of common stock net of fees |  |  |  |  |  | $ 1,300,000 | $ 200,000 |  |  |  |  |  |  |  |  |
Average sale price |  |  |  |  |  | $ 0.39 | $ 16.72 |  |  |  |  |  |  |  |  |
Warrant [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of warrants or rights issued |  |  |  |  |  | 20,000,000 |  |  |  |  |  |  |  |  |  |
Warrant [Member] | Second Funding Warrants [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity Note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of warrants vesting |  |  |  |  |  | 100.00% |  |  |  |  |  |  |  |  |  |
[1] | The Second Funding Warrants, exercisable to purchase 14.0 million shares of the Company’s common stock, were contingently issuable in connection with the Second Funding under the Orion Credit Agreement, which occurred on November 22, 2019. The Company accounted for the value of the Orion Warrants, which were exercisable to purchase an aggregate of 20.0 million shares of the Company’s common stock, as a liability as of October 31, 2019.

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