Basis of Presentation, Business and Summary of Significant Accounting Policies - Revision of Condensed Consolidated Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016	Apr. 30, 2016
Effect of the revision
Net income	$ 8,227	$ (2,212)	$ 34,614	$ 3,624	$ 12,564
Adjustments to reconcile net income to net cash used in operating activities
Deferred income tax expense			(14,773)	(6,657)
Cash used in operating activities			$ 36,340	17,902
As previously reported
Effect of the revision
Net income				2,949
Adjustments to reconcile net income to net cash used in operating activities
Deferred income tax expense				(5,982)
Cash used in operating activities				17,902
Correction to statutory tax rate used in purchase accounting for April 1, 2014 Acquisition | Adjustment
Effect of the revision
Net income				675
Adjustments to reconcile net income to net cash used in operating activities
Deferred income tax expense				$ (675)