Acquisitions - Allocation of Purchase Price (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Liabilities assumed:
Goodwill	$ 132,806	$ 128,566
Series of Individually Immaterial Business Acquisitions
Assets acquired:
Inventories	1,056
Property and equipment	20,283
Total assets	21,339
Liabilities assumed:
Accrued expenses	106
Total liabilities	106
Net tangible assets acquired	21,233
Goodwill	4,240
Total consideration paid	$ 25,473