Redeemable Preferred Stock - Series C Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended			12 Months Ended
	Feb. 21, 2019	Apr. 30, 2019	Jan. 31, 2019	Apr. 30, 2018	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017	May 23, 2019	Jan. 02, 2019	Dec. 17, 2018	Dec. 03, 2018	Aug. 27, 2018	Aug. 26, 2018
Installment And Optional Conversions Triggering Event Conversions Of Series D Preferred Stock To Common Stock [Member]
Class Of Stock [Line Items]
Convertible preferred stock, reduction in carrying amount					$ 31.2
Installment Conversion Of Series C Preferred Stock To Common Stock [Member]
Class Of Stock [Line Items]
Convertible preferred stock, reduction in carrying amount						$ 20.2
Waiver Agreement [Member]
Class Of Stock [Line Items]
Decrease in net loss attributable to common shareholders				$ 0.5
Redemption value adjustment of net loss attributable to common stockholders			$ 8.6
Series C Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares issued						8,992
Preferred stock shares outstanding						8,992		0
Temporary Equity Carrying Amount Attributable To Parent						$ 7.5
Conversion of stock conversion price												$ 18.00	$ 22.08
Adjusted conversion price						$ 18.00			$ 5.16	$ 6.00	$ 6.96
Preferred stock deemed dividends					1.5	$ 9.6
Convertible preferred stock, reduction in carrying amount					$ 15.5
Convertible preferred stock, converted into common stock					8,992	24,308
Convertible preferred stock, converted into number of common stock shares					3,914,218
Series C Preferred Stock | Minimum [Member]
Class Of Stock [Line Items]
Adjusted conversion price								$ 1.27
Series C Preferred Stock | Maximum [Member]
Class Of Stock [Line Items]
Adjusted conversion price								$ 4.45
Series C Preferred Stock | Waiver Agreement [Member]
Class Of Stock [Line Items]
Temporary Equity Carrying Amount Attributable To Parent	$ 13.5
Percentage of shares will receive upon conversion prior to execution of waiver agreement	25.00%
Conversion right description					Under the Waiver Agreement, the conversion price of the Series C Preferred Stock was stated to be the lowest of (i) $4.45, (ii) 85% of the lowest closing bid price of the Company’s common stock during the period beginning on and including the fifth trading day prior to the date on which the applicable conversion notice was delivered to the Company and ending on and including the date on which the applicable conversion notice was delivered to the Company, and (iii) 85% of the quotient of (A) the sum of the five lowest volume weighted average prices of the Company’s common stock during the 20 consecutive trading day period ending on and including the trading day immediately preceding the applicable conversion date divided by (B) five.
Conversion price of preferred stock	$ 4.45
Percentage of lowest volume weighted average price of common stock considered as conversion price	85.00%
Number of consecutive trading days	20 days
Percentage of conversion price of common stock	125.00%
Convertible preferred stock embedded conversion amount		$ 6.6
Change in fair value of convertible preferred stock	$ (0.6)
Percentage of stated redemption value adjustment					108.00%
Stated redemption value corresponding charge to common shareholders					$ 8.6
Series C Preferred Stock | Waiver Agreement [Member] | Measurement Input, Price Volatility [Member]
Class Of Stock [Line Items]
Convertible preferred stock, measurement input	75.00%
Series C Preferred Stock | Waiver Agreement [Member] | Measurement Input, Discount Rate
Class Of Stock [Line Items]
Convertible preferred stock, measurement input	20.00%
Series C Preferred Stock | Convertible Preferred Offering [Member]
Class Of Stock [Line Items]
Aggregate number of shares issued							33,500
Proceeds from Issuance of preferred stock							$ 27.9
Series C Preferred Stock | Convertible Preferred Offering [Member] | Waiver Agreement [Member]
Class Of Stock [Line Items]
Convertible preferred stock, reduction in carrying amount					$ 6.6