Cash and Cash Equivalents (Details) - USD ($)	Feb. 29, 2016	May. 31, 2015	Feb. 28, 2015	May. 31, 2014
Summary of cash and cash equivalents
Cash in banks	$ 3,074,837	$ 2,851,802
Money market funds	537,793	817,988
Total	$ 3,612,630	$ 3,669,790	$ 2,440,323	$ 2,841,967