Net Earnings (Loss) Per Share - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 26, 2019	Jan. 27, 2018	Jan. 26, 2019	Jan. 27, 2018	Dec. 14, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted	$ 0	$ 0	$ (9)	$ 0
Stock Repurchase Program, Authorized Amount					$ 50,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 26,669		$ 26,669
Shares Paid for Tax Withholding for Share Based Compensation			349,765
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,412,951	2,844,886	752,834	2,476,767
Net Income (Loss) Attributable to Parent	$ 769	$ (283,235)	$ 21,844	$ (269,623)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	0	0	(9)	0
Net Income (Loss) Available to Common Stockholders, Basic	769	(283,235)	21,835	(269,623)
Undistributed Earnings, Basic	0	0	9	0
Net Income (Loss) Attributable to Parent, Diluted	$ 769	$ (283,235)	$ 21,835	$ (269,623)
Weighted Average Number of Shares Outstanding, Basic	47,561,000	46,914,000	47,220,000	46,712,000
Weighted Average Number of Shares Outstanding, Diluted	47,937,000	46,914,000	47,772,000	46,712,000
Earnings Per Share, Basic	$ 0.02	$ (6.04)	$ 0.46	$ (5.77)
Earnings Per Share, Diluted	$ 0.02	$ (6.04)	$ 0.46	$ (5.77)
Average dilutive restricted stock units	178,000	0	403,000	0
Average dilutive performance shares	45,000	0	41,000	0
Average dilutive restricted shares	3,000	0	10,000	0
Average Dilutive Performance Share Units	150,000	0	98,000	0