Basis of Presentation, Business and Summary of Significant Accounting Policies - Deferred Taxes (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Adoption of new accounting pronouncement
Deferred income taxes, net, long-term liability	$ (26,820)	$ (41,203)
ASU 2015-17, Balance Sheet Classification of Deferred Taxes \| Adjustments for early adoption of new accounting pronouncement
Adoption of new accounting pronouncement
Deferred tax assets, current assets		11,047
Deferred income taxes, net, long-term liability		$ (11,047)

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