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Income Taxes - Additional Information (Detail) - USD ($)
 12 Months Ended
May. 31, 2015
May. 31, 2014
Income Tax Contingency [Line Items]    
Federal and state income tax benefit $ 0 $ 0
Statutory federal income tax rate 34.00% 34.00%
Federal net operating loss and tax credit carryforwards $ 33,120,000 $ 30,488,000
State net operating loss carryforwards 8,133,000 7,860,000
Interest or penalties related to income tax 0 0
Unrecognized tax benefits $ 0 $ 0
Minimum [Member] | Federal [Member]    
Income Tax Contingency [Line Items]    
Net operating loss and tax credit carryforwards life expectancy 16 years  
Minimum [Member] | State [Member]    
Income Tax Contingency [Line Items]    
Net operating loss and tax credit carryforwards life expectancy 5 years  
Maximum [Member] | Federal [Member]    
Income Tax Contingency [Line Items]    
Net operating loss and tax credit carryforwards life expectancy 20 years  
Maximum [Member] | State [Member]    
Income Tax Contingency [Line Items]    
Net operating loss and tax credit carryforwards life expectancy 20 years