Stockholders' Equity - Summary of Activity for Unvested RSUs and PSUs (Detail) - RSUs and PSUs - $ / shares	3 Months Ended
Jul. 31, 2019	Jul. 31, 2018
Summary of activity in unvested restricted stock units and performance share units
Restricted Stock Units, RSUs and PSUs outstanding, beginning of period	1,631,631	1,442,316
Restricted Stock Units, Awarded	131,771	140,771
Restricted Stock Units, Vested	(182,900)	(146,523)
Restricted Stock Units, Forfeited	(138,830)	(118,180)
Restricted Stock Units, RSUs and PSUs outstanding, end of period	1,441,672	1,318,384
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, RSUs and PSUs outstanding, beginning of period	$ 17.80	$ 17.80
Weighted Average Grant Date Fair Value, Awarded	10.65	12.35
Weighted Average Grant Date Fair Value, Vested	19.11	18.78
Weighted Average Grant Date Fair Value, Forfeited	16.11	15.53
Weighted Average Grant Date Fair Value, RSUs and PSUs outstanding, end of period	$ 15.44	$ 17.31

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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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.

+ References

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-Publisher FASB
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-Topic 718
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-Section 50
-Paragraph 2
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- Definition

The number of grants made 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

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-Publisher FASB
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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

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-Publisher FASB
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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

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-Publisher FASB
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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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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.

+ References

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