Federal Income Taxes - Summary of Deferred Taxes (Details) - USD ($)	May 31, 2018	May 31, 2017
Income Tax Disclosure [Abstract]
Net operating loss carryforward	$ 2,015,616	$ 2,102,924
Accrued expenses	101,320	113,021
Allowance for doubtful accounts		8,788
Other	27,432	27,540
Total deferred tax asset	2,144,368	2,252,273
Depreciation and amortization, tax reporting in excess of financial	(2,635,333)	(1,970,858)
Net deferred tax asset (liability)	$ (490,965)	$ 281,415

Deferred tax asset depreciation and amortization tax reporting in excess of financial.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from accrued liabilities.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the allowance for doubtful accounts.

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