Equity-Based Compensation - Stock Option Activity (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Apr. 30, 2017
Stock option activity
Outstanding, beginning of the period (in shares)	2,088
Options exercised (in shares)	161	0
Outstanding, end of the period (in shares)	1,927		2,088
Exercisable at end of period (in shares)	1,501
Expected to vest after end of period (in shares)	426
Weighted average exercise price
Outstanding, beginning of period (in dollars per share)	$ 13.49
Options exercised (in dollars per share)	12.53
Outstanding, end of the period (in dollars per share)	13.57		$ 13.49
Exercisable at end of period (in dollars per share)	12.83
Expected to vest after end of period (in dollars per share)	$ 16.17
Other disclosures
Weighted average remaining contractual life, Outstanding	6 years 8 months 23 days		7 years 2 months 23 days
Weighted average remaining contractual life, Exercisable	6 years 6 months 22 days
Weighted average remaining contractual life, Expected to vest after end of period	7 years 3 months 22 days
Aggregate intrinsic value, options outstanding	$ 39,467		$ 47,336
Aggregate intrinsic value, options exercisable at end of period	31,854
Aggregate intrinsic value, options expected to vest after end of period	7,614
Intrinsic value of stock option awards exercised	3,500
Unrecognized compensation expense	$ 1,000
Weighted average period for recognition of unrecognized compensation expense	6 months