Income Taxes - Changes in Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, beginning of year	$ 3,674	$ 2,478	$ 2,095
Settlement with tax authority	(1,771)	(708)
Additions based on tax positions related to the current year	1,775	1,116	383
Additions based on tax positions related to prior years	4,116	788
Unrecognized tax benefits, end of year	$ 7,794	$ 3,674	$ 2,478

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Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 10B
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-SubTopic 10
-Section 50
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- Definition

Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
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-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 15A
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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
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