Income Taxes - Reconciliation of effective tax rate (Details) - USD ($)	12 Months Ended
Jul. 31, 2018	Jul. 31, 2017
Income Tax Disclosure [Abstract]
Federal statutory rate	(26.50%)	(34.00%)
Increase (decrease) in income taxes resulting from:
Imputed interest income on intercompany receivables from foreign subsidiaries
Nondeductible or non-taxable items	2850.00%	2700.00%
Other temporary differences	90.00%	(100.00%)
Tax rate change	$ (88.7)
Change in valuation allowance	8960.00%	800.00%
Effective tax rate

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates.

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