Equity-Based Compensation - Stock Option Activity (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jul. 31, 2016	Jul. 31, 2015
Stock option activity
Outstanding, beginning of the period (in shares)	1,935,106
Options granted (in shares)	165,636	0
Outstanding, end of the period (in shares)	2,100,742
Exercisable (in shares)	793,757
Expected to vest (in shares)	1,306,985
Weighted average exercise price
Outstanding, beginning of period (in dollars per share)	$ 12.37
Options granted (in dollars per share)	23.11
Outstanding, end of the period (in dollars per share)	13.36
Exercisable (in dollars per share)	12.47
Expected to vest (in dollars per share)	$ 13.89
Other disclosures
Remaining contractual life, options outstanding (years)	7 years 11 months 19 days
Remaining contractual life, options exercisable (years)	7 years 9 months 7 days
Remaining contractual life, options expected to vest (years)	8 years 29 days
Aggregate intrinsic value, options outstanding	$ 24,988
Aggregate intrinsic value, options exercisable	10,145
Aggregate intrinsic value, options expected to vest	$ 14,843