Summary of Other Assets (Detail) - USD ($) $ in Thousands	May 31, 2016	May 31, 2015
Other Assets [Line Items]
Net investment in sales-type leases	$ 3,581	$ 5,876
Supplemental executive retirement plan assets	3,089	3,521
Demonstration equipment	4,851	81
Income taxes receivable	1,342	0
Prepaid and other assets	3,734	4,265
Total other assets	$ 16,597	$ 13,743