Redeemable Preferred Stock - Series D Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Jul. 03, 2019	Aug. 31, 2018	Oct. 31, 2019
Installment And Optional Conversions Triggering Event Conversions Of Series D Preferred Stock To Common Stock [Member]
Class Of Stock [Line Items]
Conversion of common stock, shares issued			62,040,496
Convertible preferred stock, reduction in carrying amount			$ 31.2
Series D Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares issued		30,680
Preferred stock, initial convertible shares		1,852,657
Conversion of stock conversion price		$ 16.56
Net proceeds from issuance of preferred shares		$ 25.3
Convertible preferred stock, converted into common stock			30,680
Preferred stock deemed dividends			$ 6.0
Preferred stock, redemption accretion value			$ 3.8
Series D Preferred Stock | Minimum [Member]
Class Of Stock [Line Items]
Preferred stock, conversion basis, stock issuance, threshold percentage of outstanding voting stock			20.00%
Reduced conversion price	$ 0.14
Series D Preferred Stock | Minimum [Member] | Convertible Preferred Offering [Member]
Class Of Stock [Line Items]
Conversion terms, prior receiving beneficial ownership, percentage			20.00%
Series D Preferred Stock | Maximum [Member]
Class Of Stock [Line Items]
Reduced conversion price	$ 0.61