Basis of Presentation, Business and Summary of Significant Accounting Policies - Effect of Inappropriate Statutory Rate (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	Apr. 30, 2015
Effect of misstatement
Deferred Tax Liabilities, Net, Noncurrent	$ 32,327		$ 32,327		$ 41,203
Goodwill	425,933		425,933		386,306	$ 348,811
Provision for (benefit from) income taxes	5,363	$ (819)	12,232	$ 4,659
Net income (loss)	$ 8,227	$ (2,212)	$ 34,614	$ 3,624	$ 12,564
Understatement resulting from misstatement | Correction to statutory tax rate used in purchase accounting for April 1, 2014 Acquisition
Effect of misstatement
Deferred Tax Liabilities, Net, Noncurrent						6,400
Goodwill						4,300
Net income (loss)						2,100
Overstatement resulting from misstatement | Correction to statutory tax rate used in purchase accounting for April 1, 2014 Acquisition
Effect of misstatement
Provision for (benefit from) income taxes						$ 2,100