Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
Leases (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Capital Leased Assets
Rent expense under operating leases	$ 1,936	$ 1,862	$ 1,961
Minimum \| Capital Lease Obligations
Capital Leased Assets
Capital lease term	5 years
Maximum \| Capital Lease Obligations
Capital Leased Assets
Capital lease term	20 years