Transactions With Related Parties - Facilities Rental (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Affiliated partnerships or entities \| Lease of office and warehouse facilities \| Selling, general and administrative expenses
Transactions with related parties
Rent expense	$ 195	$ 195	$ 585	$ 390

Amount of selling, general and administrative expenses resulting from transactions, excluding transactions that are eliminated in consolidated or combined financial statements, with related party.

No definition available.

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