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Income Taxes (Details) - USD ($)			3 Months Ended		12 Months Ended
	Jan. 31, 2018	Jan. 01, 2018	Apr. 30, 2018	Apr. 30, 2017	Jan. 31, 2019
Income Taxes (Details) [Line Items]
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Depreciation, Percent			(35.30%)	29.90%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%
Deferred Other Tax Expense (Benefit) (in Dollars)	$ (14,362,000)
Minimum [Member]
Income Taxes (Details) [Line Items]
Effective Income Tax Rate Reconciliation, Tax Credit, Percent			(25.00%)		25.00%
Maximum [Member]
Income Taxes (Details) [Line Items]
Effective Income Tax Rate Reconciliation, Tax Credit, Percent			(30.00%)		30.00%
Refined Coal [Member]
Income Taxes (Details) [Line Items]
Tax Credit To Reduce Future Income Tax Liailibities Duration			20 years

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Amount of other deferred income tax expense (benefit) pertaining to income (loss) from continuing operations. For example, but not limited to, acquisition-date income tax benefits or expenses recognized from changes in the acquirer's valuation allowance for its previously existing deferred tax assets resulting from a business combination and adjustments to beginning-of-year balance of a valuation allowance because of a change in circumstance causing a change in judgment about the realizability of the related deferred tax asset in future periods.

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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 tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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