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Income Taxes - Additional Information (Detail) - USD ($)
12 Months Ended
May 31, 2016
May 31, 2015
Income Tax Contingency [Line Items]    
Income tax expense (benefit) $ 0 $ 0
Statutory federal income tax rate 34.00% 34.00%
Federal net operating loss and tax credit carryforwards $ 32,380,000 $ 33,120,000
State net operating loss carryforwards 7,717,000 8,133,000
Interest or penalties related to income tax 0 0
Unrecognized tax benefits 0 0
Federal [Member]    
Income Tax Contingency [Line Items]    
Income tax expense (benefit) 0 0
Federal net operating loss and tax credit carryforwards 695,000  
State [Member]    
Income Tax Contingency [Line Items]    
Income tax expense (benefit) 0 $ 0
State net operating loss carryforwards $ 191,000  
Minimum [Member] | Federal [Member]    
Income Tax Contingency [Line Items]    
Net operating loss and tax credit carryforwards life expectancy 12 years  
Minimum [Member] | State [Member]    
Income Tax Contingency [Line Items]    
Net operating loss and tax credit carryforwards life expectancy 1 year  
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