Acquisitions - Additional Information (Detail) - USD ($)		3 Months Ended	9 Months Ended
	Aug. 23, 2016	Jan. 31, 2017	Jan. 31, 2017	Apr. 30, 2016
Business Acquisition [Line Items]
Business acquisition, purchase price allocate to goodwill		$ 19,549,000	$ 19,549,000	$ 18,749,000
MID Retail, Inc.
Business Acquisition [Line Items]
Business acquisition, purchase price paid in cash	$ 4,000,000
Business acquisition, post-closing working capital adjustment	385,000
Business acquisition, fair value of deferred revenue adjustment	$ 102,000
Earnout period	36 months
Additional consideration payments	$ 2,000,000
Business acquisition costs incurred		0	139,400
Business acquisition, purchase price allocate to goodwill	$ 800,000
Accrued earnout amount		$ 54,000	$ 54,000