Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Nov. 30, 2014	Feb. 29, 2016	Feb. 28, 2015
Summary Of Significant Accounting Policies [Line Items]
Rental and lease equipment impairment				$ 443	$ 0
Advertising expenses	$ 267	$ 301		857	720
Shipping and handling cost	815	$ 847		$ 2,688	$ 2,968
Assets, liabilities, revenues and expenses of foreign subsidiaries				0.1
Restatement of Prior Year Income, Gross			$ 1,300
Minimum
Summary Of Significant Accounting Policies [Line Items]
Operating lease agreements Period				1 year
Finance lease agreements Period				1 year
Maximum
Summary Of Significant Accounting Policies [Line Items]
Operating lease agreements Period				3 years
Finance lease agreements Period				3 years
Period for demonstration equipment included in other assets				2 years
T&M
Summary Of Significant Accounting Policies [Line Items]
Rental and lease equipment impairment	$ 0			$ 443