Stockholders' Equity - Reconciliation of Net Income Amounts and Weighted Average Number of Common and Common Equivalent Shares Used to Determine Basic and Diluted Earnings per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Jul. 31, 2019	Jul. 31, 2018
Earnings Per Share [Abstract]
Net (loss)/income	$ (2,108)	$ 7,645
Basic earnings, Shares	54,783	54,345
Effect of dilutive stock awards, Shares		586
Diluted earnings, Shares	54,783	54,931
Basic earnings, Per Share Amount	$ (0.04)	$ 0.14
Diluted earnings, Per Share Amount	$ (0.04)	$ 0.14