Basis of Presentation, Business and Summary of Significant Accounting Policies - Revision of Condensed Consolidated Statement of Operations (Details) - USD ($) $ / shares in Units, $ 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
Provision for income taxes	$ 5,363	$ (819)	$ 12,232	$ 4,659
Net income	$ 8,227	$ (2,212)	$ 34,614	$ 3,624	$ 12,564
Net income (loss) per share:
Basic (in dollars per share)	$ 0.20	$ (0.07)	$ 0.86	$ 0.11
Diluted (in dollars per share)	$ 0.20	$ (0.07)	$ 0.85	$ 0.11
As previously reported
Effect of the revision
Provision for income taxes				$ 5,334
Net income				$ 2,949
Net income (loss) per share:
Basic (in dollars per share)				$ 0.09
Diluted (in dollars per share)				$ 0.09
Adjustment | Correction to statutory tax rate used in purchase accounting for April 1, 2014 Acquisition
Effect of the revision
Provision for income taxes				$ (675)
Net income				$ 675
Net income (loss) per share:
Basic (in dollars per share)				$ 0.02
Diluted (in dollars per share)				$ 0.02