Reconciliation of Basic and Diluted Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 26, 2019	Jan. 27, 2018	Jan. 26, 2019	Jan. 27, 2018
Numerator for basic income (loss) per share:
Net income (loss)	$ 66,930	$ (63,536)	$ 22,498	$ (104,408)
Less allocation of dividends to participating securities	(25)	(21)	(69)	(59)
Less allocation of undistributed earnings to participating securities	(130)
Net income (loss) available to common shareholders	66,775	(63,557)	22,429	(104,467)
Numerator for diluted income (loss) per share:
Net income (loss) available to common shareholders	66,775	(63,557)	22,429	(104,467)
Allocation of undistributed earnings to participating securities	130
Less diluted allocation of undistributed earnings to participating securities	(129)
Net income (loss) available to common shareholders	$ 66,776	$ (63,557)	$ 22,429	$ (104,467)
Denominator for basic income (loss) per share:
Basic weighted average common shares	73,022	72,649	72,881	72,566
Denominator for diluted income (loss) per share:
Basic weighted average common shares	73,022	72,649	72,881	72,566
Average dilutive options	0	0	0	0
Average dilutive non-participating securities	295		194
Diluted weighted average common shares	73,317	72,649	73,075	72,566
Income (loss) per common share:
Basic	$ 0.91	$ (0.87)	$ 0.31	$ (1.44)
Diluted	$ 0.91	$ (0.87)	$ 0.31	$ (1.44)