Cash and Cash Equivalents (Details) - USD ($)	Nov. 30, 2015	May. 31, 2015	Nov. 30, 2014	May. 31, 2014
Summary of cash and cash equivalents
Cash in banks	$ 4,145,310	$ 2,851,802
Money market funds	534,917	817,988
Total	$ 4,680,227	$ 3,669,790	$ 4,009,427	$ 2,841,967