Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, netted by jurisdiction and classified as current.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=75116654&loc=d3e31917-109318

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=75116654&loc=d3e31931-109318

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32537-109319

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Organization and Significant Accounting Policies Recently Adopted Accounting Standards (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
New accounting standard
Non-current deferred income tax liabilities	$ 116
Retained earnings	219,929	$ 207,450
Accounting Standards Update 2015-17
New accounting standard
Non-current deferred income tax liabilities	(5,432)
Accounting Standards Update 2016-09
New accounting standard
Current deferred income tax assets	265
Previously reported \| Accounting Standards Update 2015-17
New accounting standard
Current deferred income tax assets	(5,432)
Previously reported \| Accounting Standards Update 2016-09
New accounting standard
Retained earnings	$ 265