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, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019	Apr. 30, 2019
Other disclosures
Equity-based compensation	$ 1,465	$ 1,140	$ 5,175	$ 2,638
Selling, general and administrative expenses
Other disclosures
Equity-based compensation			$ 4,800	2,400
Stock Options
Number of Options
Outstanding, beginning of the period (in shares)			2,080
Options granted (in shares)			386
Options exercised (in shares)			(619)
Options forfeited (in shares)			(103)
Outstanding, end of the period (in shares)	1,744		1,744		2,080
Exercisable at end of period (in shares)	1,184		1,184
Vested and expected to vest at end of period (in shares)	1,736		1,736
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share)			$ 16.34
Options granted (in dollars per share)			21.63
Options exercised (in dollars per share)			13.37
Options forfeited (in dollars per share)			25.73
Outstanding, end of the period (in dollars per share)	$ 17.98		17.98		$ 16.34
Exercisable at end of period (in dollars per share)	15.50		15.50
Vested and expected to vest at end of period (in dollars per share)	$ 17.96		$ 17.96
Other disclosures
Weighted Average Remaining Contractual Life, Outstanding (in years)			6 years 4 months 2 days		6 years 1 month 24 days
Weighted Average Remaining Contractual Life, Exercisable at end of period (in years)			5 years 25 days
Weighted Average Remaining Contractual Life, Vested and expected to vest at end of period (in years)			6 years 3 months 29 days
Aggregate Intrinsic Value, Outstanding	$ 15,938		$ 15,938		$ 7,615
Aggregate Intrinsic Value, Exercisable at end of period	13,698		13,698
Aggregate Intrinsic Value, Vested and expected to vest at end of period	15,916		15,916
Intrinsic value of options exercised			9,400	$ 800
Unrecognized compensation cost	$ 4,200		$ 4,200
Weighted-average period for recognition of unrecognized compensation expense (in years)			2 years 2 months 12 days