Shareholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended	9 Months Ended
	May 03, 2017	Jul. 31, 2017	Jul. 31, 2017	Oct. 31, 2016	Jul. 31, 2016
NRG Energy, Inc. [Member]
Stockholders' Equity Note
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 40.20	$ 40.20
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		200,000	200,000
Warrants expiration date			Jul. 30, 2017
Series C Warrants [Member]
Stockholders' Equity Note
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		12,000,000	12,000,000
Series D Warrants [Member]
Stockholders' Equity Note
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		10,622,460	10,622,460
Series A Warrants [Member]
Stockholders' Equity Note
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 5.83	$ 5.83
Class of Warrant or Right, Outstanding		7,680,000	7,680,000
Series B Warrants [Member]
Stockholders' Equity Note
Class of Warrant or Right, Outstanding		4,926,000	4,926,000	3,826,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					4,926,000
Underwritten Public Offering [Member]
Stockholders' Equity Note
Stock issued during period, shares, new issues	12,000,000
Gross proceeds from common stock and warrants	$ 15.4
Common stock price per share	$ 1.28
Net proceeds from common stock and warrants	$ 13.9
Underwritten Public Offering [Member] | Series C Warrants [Member]
Stockholders' Equity Note
Class of warrants or rights issued	12,000,000
Warrants issued, price per share	$ 1.28
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 1.28
Class of warrant or right term	1 year
Underwritten Public Offering [Member] | Series D Warrants [Member]
Stockholders' Equity Note
Class of warrants or rights issued	12,000,000
Warrants issued, price per share	$ 1.28
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 1.60
Class of warrant or right term	5 years
Common Stock [Member]
Stockholders' Equity Note
Stock issued during period, shares, new issues			7,200,000
Stock issued during period on open market, net of fees			$ 12.4
Common Stock [Member] | Underwritten Public Offering [Member] | Series D Warrants [Member]
Stockholders' Equity Note
Stock issued during period, shares, new issues		1,377,540
Net proceeds from common stock and warrants		$ 1.8