Stockholders' Equity - RSU Activity (Detail) - RSUs	3 Months Ended
Dec. 31, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Outstanding, Beginning Balance (in shares) \| shares	2,357,021
Granted (in shares) \| shares	915,779
Settled (in shares) \| shares	(449,622)
Canceled (in shares) \| shares	(36,926)
Outstanding, Ending Balance (in shares) \| shares	2,786,252
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Outstanding, Beginning Balance (in dollars per share) \| $ / shares	$ 5.65
Granted (in dollars per share) \| $ / shares	8.60
Settled (in dollars per share) \| $ / shares	4.83
Canceled (in dollars per share) \| $ / shares	8.21
Outstanding, Ending Balance (in dollars per share) \| $ / shares	$ 6.69

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).

+ References

+ Details

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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

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

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 non-option equity instruments exercised by participants.

+ References

+ Details

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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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- Definition

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

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- Definition

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

+ References

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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- Definition

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+ References

No definition available.

+ Details

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