Equity-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020	Apr. 30, 2020
Other disclosures
Equity-based compensation	$ 1,877	$ 1,465	$ 6,734	$ 5,175
Selling, general and administrative expenses
Other disclosures
Equity-based compensation			$ 6,300	4,800
Stock Options
Number of Options
Outstanding, beginning of the period (in shares)			1,487
Options granted (in shares)			321
Options exercised (in shares)			(195)
Options forfeited (in shares)			(48)
Outstanding, end of the period (in shares)	1,565		1,565		1,487
Exercisable at end of period (in shares)	948		948
Vested and expected to vest at end of period (in shares)	1,558		1,558
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share)			$ 18.85
Options granted (in dollars per share)			23.43
Options exercised (in dollars per share)			17.53
Options forfeited (in dollars per share)			25.97
Outstanding, end of the period (in dollars per share)	$ 19.73		19.73		$ 18.85
Exercisable at end of period (in dollars per share)	17.65		17.65
Vested and expected to vest at end of period (in dollars per share)	$ 19.72		$ 19.72
Other disclosures
Weighted Average Remaining Contractual Life, Outstanding (in years)			6 years 6 months		6 years 4 months 24 days
Weighted Average Remaining Contractual Life, Exercisable at end of period (in years)			4 years 10 months 24 days
Weighted Average Remaining Contractual Life, Vested and expected to vest at end of period (in years)			6 years 6 months
Aggregate Intrinsic Value, Outstanding	$ 14,933		$ 14,933		$ 3,895
Aggregate Intrinsic Value, Exercisable at end of period	11,176		11,176
Aggregate Intrinsic Value, Vested and expected to vest at end of period	14,895		14,895
Intrinsic value of options exercised			2,500	$ 9,400
Unrecognized compensation cost	$ 4,600		$ 4,600
Weighted-average period for recognition of unrecognized compensation expense (in years)			2 years