Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014
Income Tax Disclosure [Abstract]
Operating loss carryforwards	$ 65,241
Alternative minimum tax credit carryforwards	167
Valuation allowance	84	$ 228
Valuation allowance, increase (decrease)	(144)	228
Out of period adjustment			$ 2,760
Unrecognized tax benefits	6,484	8,043	$ 9,244
Unrecognized tax benefits that would impact effective tax rate	4,251
Increase (decrease) in unrecognized tax benefits	(1,559)
Accrued interest and penalties	217	152
Increase in tax expense	(65)	$ (250)
Decrease in unrecognized tax benefits is reasonable possible	$ 3,198

Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations.

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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 revisions of previously reported income tax expense (benefit).

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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The net amount of all increases and decreases in unrecognized tax benefits for the period.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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