Equity-Based Compensation - Black Scholes Options - Pricing Model (Details) - $ / shares	12 Months Ended
Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Fair Value Assumptions
Dividends declared (in dollars per share)	$ 0	$ 0	$ 0
Stock options
Fair Value Assumptions
Dividend yield	0.00%
Volatility	40.68%
Expected life (years)	6 years
Risk-free interest rate	1.55%

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Risk-free interest rate assumption used in valuing an instrument.

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Weighted average expected volatility of stock price.

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