Summary of Significant Accounting Policies (Details) - USD ($)	May 31, 2017	May 31, 2016	May 31, 2015
Summary of cash and cash equivalents
Cash in banks	$ 4,634,245	$ 3,974,007
Money market funds	840,731	540,150
Certificates of deposit	249,000
Total	$ 5,723,976	$ 4,514,157	$ 3,669,790