Employee Benefit Plan - Additional Information (Detail) - Employee Savings Plan - USD ($)	3 Months Ended
Aug. 31, 2017	Aug. 31, 2016
Defined Contribution Plan Disclosure [Line Items]
Qualified non-elective contribution	3.00%
Qualified non-elective contribution expense	$ 10,800	$ 8,800

Amount of cost for defined contribution plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

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