Equity-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Other disclosures
Equity-based compensation	$ 3,906	$ 1,695	$ 2,534
Selling, general and administrative expenses
Other disclosures
Equity-based compensation	$ 3,600	$ 1,700	2,400
Stock Options
Number of Options
Outstanding, beginning of the period (in shares)	1,952
Options granted (in shares)	374
Options exercised (in shares)	(205)
Options forfeited (in shares)	(41)
Outstanding, end of the period (in shares)	2,080	1,952
Exercisable at end of period (in shares)	1,644
Vested and expected to vest at end of period (in shares)	2,073
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share)	$ 14.37
Options granted (in dollars per share)	25.58
Options exercised (in dollars per share)	12.36
Options forfeited (in dollars per share)	27.00
Outstanding, end of the period (in dollars per share)	16.34	$ 14.37
Exercisable at end of period (in dollars per share)	13.66
Vested and expected to vest at end of period (in dollars per share)	$ 16.30
Other disclosures
Weighted Average Remaining Contractual Life, Outstanding (in years)	6 years 1 month 24 days	6 years 6 months 7 days
Weighted Average Remaining Contractual Life, Exercisable at end of period (in years)	5 years 4 months 28 days
Weighted Average Remaining Contractual Life, Vested and expected to vest at end of period (in years)	6 years 1 month 21 days
Aggregate Intrinsic Value, Outstanding	$ 7,615	$ 33,209
Aggregate Intrinsic Value, Exercisable at end of period	7,615
Aggregate Intrinsic Value, Vested and expected to vest at end of period	7,615
Intrinsic value of options exercised	1,600	$ 4,300	$ 600
Unrecognized compensation cost	$ 2,900
Weighted-average period for recognition of unrecognized compensation expense (in years)	2 years 1 month 6 days