Benefit Plans - Summary of RSA and RSU Activity (Details)	12 Months Ended
Oct. 31, 2017 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Restricted Stock Awards and Units, Outstanding, Shares, Beginning Balance \| shares	990,035
Restricted Stock Awards and Units, Granted, Shares \| shares	2,510,216
Restricted Stock Awards and Units, Vested, Shares \| shares	392,458
Restricted Stock Awards and Units, Forfeited, Shares \| shares	99,107
Restricted Stock Awards and Units, Outstanding, Shares, Ending Balance \| shares	3,008,686
Restricted Stock Awards and Units, Outstanding, Weighted-Average Fair Value, Beginning Balance \| $ / shares	$ 9.52
Restricted Stock Awards and Units, Granted, Weighted-Average Fair Value \| $ / shares	1.48
Restricted Stock Awards and Units, Vested, Weighted-Average Fair Value \| $ / shares	12.39
Restricted Stock Awards and Units, Forfeited, Weighted-Average Fair Value \| $ / shares	6.62
Restricted Stock Awards and Units, Outstanding, Weighted-Average Fair Value, Ending Balance \| $ / shares	$ 2.52

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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- Definition

Number of shares under non-option equity instrument agreements that were cancelled as a result of occurrence of a terminating event.

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Net number of non-option equity instruments granted to participants.

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Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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