Income Taxes (Details) - USD ($) $ in Millions	6 Months Ended
Oct. 31, 2018	Oct. 31, 2017	Apr. 30, 2018
Effective income tax rate (as a percent)	24.50%	37.50%
Valuation allowance	$ 0.4		$ 0.4
Income tax benefit adjustment	0.1
Reserve for uncertain tax positions	$ 0.0		$ 0.0
Domestic
Federal statutory rate (as a percent)	21.00%

Amount of tax adjustment related to Tax Cuts and Jobs Act of 2017.

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- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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-Subparagraph (c)
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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
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-Paragraph 1
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- Definition

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.

+ References

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-Publisher FASB
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